chore(addons): retire the Memory add-on package

Memory is built in. Drop the package matrix, the catalog template and the
entry in the generated library index, and stop building it in the package
workflow, so the add-on is no longer offered for a new install. The sources
stay as the fixture of copies that are still installed: the host keeps the
alias that maps the legacy id to the built-in provider, and the add-on page
keeps its notice that memory is built in. The inventories and the docs follow.

Assisted-by: Claude:claude-sonnet-5-5

.github/workflows/addons-package.yml

@@ -117,7 +117,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        addon: [tables, voice, face, fine-tuning, quantization, studio, talk, telegram, slack, discord, github, home-assistant, jellyfin, office, pikvm, sandbox, web, memory]
+        addon: [tables, voice, face, fine-tuning, quantization, studio, talk, telegram, slack, discord, github, home-assistant, jellyfin, office, pikvm, sandbox, web]
     steps:
       - uses: actions/checkout@v7
         with:
@@ -236,7 +236,7 @@ jobs:
           # event it fails the plan. A missing or malformed platform file, or
           # any other error, fails the plan on every event.
           include='[]'
-          for id in tables voice face fine-tuning quantization studio talk telegram slack discord github home-assistant jellyfin office pikvm sandbox web memory; do
+          for id in tables voice face fine-tuning quantization studio talk telegram slack discord github home-assistant jellyfin office pikvm sandbox web; do
             cfg="addons/$id/package/platforms.yaml"
             err="matrix-$id.err"
             if rows=$(go run ./scripts/addons/cmd/addonpkg matrix --config "$cfg" 2>"$err"); then