refactor(registry): B2 migrate to LiteLLM-style schema — unified models[] with kind field

- 71 registry files: flat `media.*Config.models` → `models[]` with `kind` field
- `media` wrapper removed → serviceKinds, *Config fields promoted top-level
- `type` field renamed to `kind` (llm/image/tts/stt/embedding/embedding/video/music)
- providers/index.js: PROVIDER_MEDIA now built from flat top-level media fields
- shared/constants/providers.js: buildProviderEntry reads flat top-level media fields
- route /v1/models: modelKind() uses kind||type; removed subConfig merge block
- models/info route: removed sub-config fallback lookup (all models in PROVIDER_MODELS)
- ttsProviders/index.js: synthesizeViaConfig reads tts models from PROVIDER_MODELS
- test-models route, helpers.js, validate route: kind||type compat
- Baselines: PROVIDERS 62/62 ✅, Alias 90/90 ✅

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/providers/registry/nebius.js

@@ -1,35 +1,25 @@
-
 export default {
-  "id": "nebius",
-  "alias": "nebius",
+  id: "nebius",
+  alias: "nebius",
   display: {
-      "name": "Nebius AI",
-      "icon": "cloud",
-      "color": "#6C5CE7",
-      "textIcon": "NB",
-      "website": "https://nebius.com",
-      "notice": {
-          "apiKeyUrl": "https://studio.nebius.com/settings/api-keys"
-      }
+    name: "Nebius AI",
+    icon: "cloud",
+    color: "#6C5CE7",
+    textIcon: "NB",
+    website: "https://nebius.com",
+    notice: {
+      apiKeyUrl: "https://studio.nebius.com/settings/api-keys",
+    },
   },
   category: "apikey",
   authType: "apikey",
-  "transport": {
-    "baseUrl": "https://api.studio.nebius.ai/v1/chat/completions",
-    "validateUrl": "https://api.studio.nebius.ai/v1/models"
+  transport: {
+    baseUrl: "https://api.studio.nebius.ai/v1/chat/completions",
+    validateUrl: "https://api.studio.nebius.ai/v1/models",
   },
-  media: {
-    embeddingConfig: { baseUrl: "https://api.tokenfactory.nebius.com/v1/embeddings" }
-  },
-  "models": [
-    {
-      "id": "meta-llama/Llama-3.3-70B-Instruct",
-      "name": "Llama 3.3 70B Instruct"
-    },
-    {
-      "id": "Qwen/Qwen3-Embedding-8B",
-      "name": "Qwen3 Embedding 8B",
-      "type": "embedding"
-    }
-  ]
+  models: [
+    { id: "meta-llama/Llama-3.3-70B-Instruct", name: "Llama 3.3 70B Instruct" },
+    { id: "Qwen/Qwen3-Embedding-8B", name: "Qwen3 Embedding 8B", kind: "embedding" },
+  ],
+  embeddingConfig: { baseUrl: "https://api.tokenfactory.nebius.com/v1/embeddings" },
 };