feat(gallery): add nanbeige4.1-3b meta entry with hardware-resolved variants

Adds the first real meta entry to the gallery index. It resolves to the
Q8_0 build on hosts with at least 6GiB of VRAM and to the Q4_K_M build
everywhere else, installing either payload under the stable name
nanbeige4.1-3b.

The entry carries a url equal to its final candidate's url. LocalAI
releases that predate candidates support parse the index non-strictly
and drop the key silently, so without that url they would list the entry
and install nothing. A regression spec parses the index the way those
releases do and asserts every meta entry stays installable for them.

Also teaches core/schema/gallery-model.schema.json about candidates. The
schema sets additionalProperties: false at the top level, so an author
following CONTRIBUTING.md and adding the yaml-language-server comment
would otherwise get a validation error on this entry.

Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

core/gallery/meta_install_test.go

@@ -368,3 +368,40 @@ var _ = Describe("InstallModelFromGallery with meta entries", func() {
 		Expect(record.URLs).To(ConsistOf("https://example.invalid/qwen3"))
 	})
 })
+
+var _ = Describe("legacy client compatibility", func() {
+	It("exposes a url on every meta entry to clients that ignore candidates", func() {
+		data, err := os.ReadFile(filepath.Join("..", "..", "gallery", "index.yaml"))
+		Expect(err).ToNot(HaveOccurred())
+
+		// Parse exactly as an older LocalAI release would: non-strictly, with
+		// no knowledge of the candidates key.
+		var legacy []struct {
+			Name string `yaml:"name"`
+			URL  string `yaml:"url"`
+		}
+		Expect(yaml.Unmarshal(data, &legacy)).To(Succeed())
+
+		var current []gallery.GalleryModel
+		Expect(yaml.Unmarshal(data, &current)).To(Succeed())
+
+		urlByName := map[string]string{}
+		for _, e := range legacy {
+			urlByName[e.Name] = e.URL
+		}
+
+		metaCount := 0
+		for _, e := range current {
+			if !e.IsMeta() {
+				continue
+			}
+			metaCount++
+			// Without a url an old client lists the entry and installs an
+			// empty model, because it silently drops candidates.
+			Expect(urlByName[e.Name]).ToNot(BeEmpty(),
+				"meta entry %q is invisible payload-wise to older clients", e.Name)
+		}
+		Expect(metaCount).To(BeNumerically(">", 0),
+			"expected at least one meta entry in the gallery index")
+	})
+})

core/schema/gallery-model.schema.json

@@ -56,6 +56,42 @@
         "additionalProperties": false
       }
     },
+    "candidates": {
+      "type": "array",
+      "description": "Ordered variant list of a meta entry. The first candidate the host satisfies is installed, under the meta entry's own name. An entry carrying candidates must not also carry files or config_file.",
+      "minItems": 1,
+      "items": {
+        "type": "object",
+        "required": ["model"],
+        "properties": {
+          "model": {
+            "type": "string",
+            "description": "Name of a concrete (non-meta) gallery entry"
+          },
+          "capability": {
+            "type": "string",
+            "description": "Host capability this candidate requires, matched exactly and case-sensitively (for example metal, nvidia-cuda-12). Absent matches any host."
+          },
+          "min_vram": {
+            "type": "string",
+            "description": "Authored VRAM floor, for example 20GiB. Authoritative: inference never overwrites it."
+          },
+          "backend": {
+            "type": "string",
+            "description": "Denormalized by the nightly job for display. Never authored by hand."
+          },
+          "quantization": {
+            "type": "string",
+            "description": "Denormalized by the nightly job for display. Never authored by hand."
+          },
+          "inferred_min_vram": {
+            "type": "string",
+            "description": "Denormalized by the nightly job as a fallback floor. Never authored by hand; min_vram wins."
+          }
+        },
+        "additionalProperties": false
+      }
+    },
     "prompt_templates": {
       "type": "array",
       "description": "Prompt templates written as .tmpl files",