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/opencode.js

@@ -1,28 +1,23 @@
-
 export default {
-  "id": "opencode",
-  "alias": "oc",
+  id: "opencode",
+  alias: "oc",
+  uiAlias: "oc",
   display: {
-      "name": "OpenCode Free",
-      "icon": "terminal",
-      "color": "#E87040",
-      "textIcon": "OC"
+    name: "OpenCode Free",
+    icon: "terminal",
+    color: "#E87040",
+    textIcon: "OC",
   },
   category: "free",
-  uiAlias: "oc",
   noAuth: true,
-  passthroughModels: true,
-  "transport": {
-    "baseUrl": "https://opencode.ai",
-    "headers": {
-      "x-opencode-client": "desktop"
+  transport: {
+    baseUrl: "https://opencode.ai",
+    headers: {
+      "x-opencode-client": "desktop",
     },
-    "noAuth": true
-  },
-  media: {
     noAuth: true,
-    passthroughModels: true,
-    modelsFetcher: { url: "https://opencode.ai/zen/v1/models", type: "opencode-free" }
   },
-  "models": []
+  models: [],
+  modelsFetcher: { url: "https://opencode.ai/zen/v1/models", type: "opencode-free" },
+  passthroughModels: true,
 };