refactor(paged): stock llama-cpp is patch-free; paged backend owns its patch series

Move ALL paged-attention content out of the stock backend/cpp/llama-cpp
backend and into backend/cpp/llama-cpp-localai-paged, so the stock backend is
pure upstream llama.cpp and the paged backend owns and applies its own vendored
patch series.

- Delete the dead early-exploration scaffold backend/cpp/llama-cpp/paged/
  (kernel/w4a16 Marlin scaffold, standalone paged_kv_manager, bench/loadgen,
  its own 0001-0002 patches, dense-era design docs, tests). Zero references
  repo-wide.
- Move backend/cpp/llama-cpp/patches/ (the 28-patch paged series + paged/README
  + 3 operational docs, plus the kernel/ scaffold patch and the top-level paged
  README/BENCHMARKS) to backend/cpp/llama-cpp-localai-paged/patches/. The stock
  backend keeps no patches/ dir; it had no non-paged base patches.
- Purify the stock backend: remove the LLAMA_PAGED make variable, the
  patches/paged apply loop, and the LLAMA_PAGED passthrough to prepare.sh;
  remove the paged-series handling from prepare.sh. The stock llama.cpp target
  now only clones the pin and applies its own (currently empty) base patches/
  series. The runtime paged option hooks in the shared grpc-server.cpp are
  untouched (inert without the patches).
- The paged backend's Makefile now applies its OWN patches/paged/0*.patch onto
  each freshly cloned tree via strict git apply (apply-paged-patches), after the
  copied stock infra clones the pin and applies base patches.
- Repoint every reference to the old patches/paged path: the upstream canary
  workflow + apply script, bump_deps.yaml, gallery/index.yaml, the docs,
  backend/index.yaml, backend-matrix.yml, the top-level Makefile comments, and
  the moved PIN_SYNC / README docs. Drop the now-removed LLAMA_PAGED=on
  build-toggle from comments.

Verified: the full 28-patch series applies strict-clean (git apply, exit 0) to
a clean ggml-org/llama.cpp checkout at the pinned c299a92c, and the repointed
canary apply script resolves and applies the series end to end.

Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

.github/backend-matrix.yml

@@ -5073,7 +5073,7 @@ includeDarwin:
     lang: "go"
   # llama-cpp-localai-paged on Darwin: same bespoke CPU_ALL_VARIANTS + Metal build
   # as stock llama-cpp (driven by make backends/llama-cpp-localai-paged-darwin),
-  # reusing backend/cpp/llama-cpp sources with LLAMA_PAGED=on. lang=go selects the
+  # reusing backend/cpp/llama-cpp sources, with the paged patch series applied by the wrapper. lang=go selects the
   # runner/toolchain only; the source path is C++. Metal delivers paged-KV (the
   # NVFP4 FP4-MMA fast path is CUDA/Blackwell-only) and the GDN/conv fused ops have
   # no Metal kernel, so a gated-DeltaNet (qwen35) model falls back to the CPU

.github/scripts/paged-canary-apply.sh

@@ -1,14 +1,14 @@
 #!/usr/bin/env bash
 #
 # paged-canary-apply.sh - apply the vendored paged-attention patch series
-# (backend/cpp/llama-cpp/patches/paged/0001-0030) to a llama.cpp checkout, the
+# (backend/cpp/llama-cpp-localai-paged/patches/paged/0001-0030) to a llama.cpp checkout, the
 # same way the build does, but tolerating the ONE known-benign pre-existing
 # quirk in the series. Used by the early-warning canary
 # (.github/workflows/llama-cpp-paged-canary.yml) so it only goes red on a REAL
 # upstream break, never on that quirk.
 #
 # Usage: paged-canary-apply.sh <llama.cpp-checkout-dir> <patches-dir>
-#   <patches-dir> is normally backend/cpp/llama-cpp/patches (it holds the
+#   <patches-dir> is normally backend/cpp/llama-cpp-localai-paged/patches (it holds the
 #   top-level base series 0*.patch, currently empty, and the paged/ subseries).
 #
 # Exit 0  = the whole series applied -> patches still fit upstream.
@@ -27,7 +27,7 @@
 # missing-file hunk rejects the whole patch - and because 0021/0022/0026/0028
 # build on 0019's code, the rejection cascades to them too. This is a
 # PRE-EXISTING shipped-series defect, present identically on every pin, NOT an
-# upstream break (see backend/cpp/llama-cpp/patches/paged/PIN_SYNC_c299a92c.md
+# upstream break (see backend/cpp/llama-cpp-localai-paged/patches/paged/PIN_SYNC_c299a92c.md
 # and README.md). We exclude ONLY that dev-doc path and still
 # apply 0019's real code hunks atomically, so a genuine code-hunk break in 0019
 # still fails the canary. prepare.sh tolerates the same hunk via
@@ -53,7 +53,7 @@ apply_one() {
   echo "paged-canary: applying $(basename "$p")"
   if ! git apply --verbose "$@" "$p"; then
     echo "::error::paged patch no longer applies to the upstream llama.cpp tip: $(basename "$p")"
-    echo "::error::upstream drifted past the vendored paged series - run a PIN_SYNC (backend/cpp/llama-cpp/patches/paged/PIN_SYNC_c299a92c.md), do NOT bump the pin blindly"
+    echo "::error::upstream drifted past the vendored paged series - run a PIN_SYNC (backend/cpp/llama-cpp-localai-paged/patches/paged/PIN_SYNC_c299a92c.md), do NOT bump the pin blindly"
     exit 1
   fi
 }

.github/workflows/bump_deps.yaml

@@ -11,7 +11,7 @@ jobs:
       matrix:
         # NOTE: there is intentionally NO entry for the llama-cpp-localai-paged
         # backend. It carries a vendored paged-attention patch series
-        # (backend/cpp/llama-cpp/patches/paged/) hand-verified bit-exact against
+        # (backend/cpp/llama-cpp-localai-paged/patches/paged/) hand-verified bit-exact against
         # ONE specific llama.cpp tip; a naive nightly bump would move the tip out
         # from under the patches and break `git apply` at build time. Its pin is
         # therefore decoupled (its own LLAMA_VERSION in

.github/workflows/llama-cpp-paged-canary.yml

@@ -1,7 +1,7 @@
 name: 'llama.cpp paged patches: upstream canary'
 
 # EARLY-WARNING CANARY for the vendored paged-attention patch series
-# (backend/cpp/llama-cpp/patches/paged/0001-0030).
+# (backend/cpp/llama-cpp-localai-paged/patches/paged/0001-0030).
 #
 # WHY THIS EXISTS
 # The paged backend (backend/cpp/llama-cpp-localai-paged) pins its OWN verified
@@ -17,7 +17,7 @@ name: 'llama.cpp paged patches: upstream canary'
 # RED HERE means: time to run a PIN_SYNC (rebase the patches onto the new tip,
 # pass the bit-exact gate on the GPU, re-export the .patch files, THEN advance
 # the pin in backend/cpp/llama-cpp-localai-paged/Makefile). See
-# backend/cpp/llama-cpp/patches/paged/PIN_SYNC_c299a92c.md.
+# backend/cpp/llama-cpp-localai-paged/patches/paged/PIN_SYNC_c299a92c.md.
 #
 # SIGNAL-ONLY: this workflow moves no pinned version, ships nothing, and is fully
 # decoupled from bump_deps - so the main dep-bump PR stays green regardless. A
@@ -91,7 +91,7 @@ jobs:
         run: |
           bash .github/scripts/paged-canary-apply.sh \
             /tmp/llama.cpp \
-            "$PWD/backend/cpp/llama-cpp/patches"
+            "$PWD/backend/cpp/llama-cpp-localai-paged/patches"
           echo "- apply: full paged series applies to the upstream tip :white_check_mark:" >> "$GITHUB_STEP_SUMMARY"
 
   compile:
@@ -141,12 +141,16 @@ jobs:
               cp -a /opt/grpc/. /usr/local/
 
               # Pre-populate the llama.cpp checkout at the latest tip with the
-              # paged series applied via the tolerant canary apply (so the benign
-              # 0019 dev-doc hunk does not abort the build). Because
-              # backend/cpp/llama-cpp/llama.cpp now exists, the Makefile
-              # llama.cpp target (strict clone + git apply) is skipped and
-              # prepare.sh sees the paged sentinel and skips re-applying - so we
-              # drive the REAL grpc-server build path on top of our apply.
+              # paged series applied via the tolerant canary apply. Because
+              # backend/cpp/llama-cpp/llama.cpp now exists, the stock Makefile's
+              # llama.cpp target (clone + base-patch apply) is skipped and the
+              # now patch-free prepare.sh only copies the grpc-server sources -
+              # so we drive the REAL grpc-server build path on top of our paged
+              # apply. The stock llama-cpp backend no longer carries the paged
+              # series (it lives in backend/cpp/llama-cpp-localai-paged/patches/
+              # paged); we build it here in the stock dir only because that is
+              # where the shared build infra (Makefile / grpc-server.cpp /
+              # CMakeLists.txt / prepare.sh) lives.
               cd backend/cpp/llama-cpp/
               mkdir -p llama.cpp
               cd llama.cpp
@@ -157,15 +161,16 @@ jobs:
               cd /LocalAI
               bash .github/scripts/paged-canary-apply.sh \
                 backend/cpp/llama-cpp/llama.cpp \
-                "$PWD/backend/cpp/llama-cpp/patches"
+                "$PWD/backend/cpp/llama-cpp-localai-paged/patches"
 
               # Cheapest real CUDA build that proves the patches compile: one
-              # CUDA arch, cublas, paged on. CMAKE_ARGS is passed via the
-              # environment (not as a make arg) so the Makefile += flags are
-              # still appended, exactly like .docker/llama-cpp-localai-paged-compile.sh.
+              # CUDA arch, cublas. CMAKE_ARGS is passed via the environment (not
+              # as a make arg) so the Makefile += flags are still appended,
+              # exactly like .docker/llama-cpp-localai-paged-compile.sh. The paged
+              # series is already applied to the checkout above, so the stock
+              # build just compiles the patched tree.
               cd backend/cpp/llama-cpp/
               BUILD_TYPE=cublas \
-              LLAMA_PAGED=on \
               CMAKE_ARGS="-DCMAKE_CUDA_ARCHITECTURES=80" \
               make grpc-server
               test -x grpc-server