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>

src/app/api/providers/[id]/test-models/route.js

@@ -44,14 +44,14 @@ export async function POST(request, { params }) {
     // Warm up with first model to trigger token refresh (if needed) before parallel calls.
     // This prevents race condition where multiple requests concurrently refresh the same token.
     const [first, ...rest] = models;
-    const firstKind = first.type || "llm";
+    const firstKind = first.kind || first.type || "llm";
     const firstResult = await pingModelByKind(`${alias}/${first.id}`, firstKind, baseUrl);
     const results = [{ modelId: first.id, name: first.name || first.id, ...firstResult }];
 
     if (rest.length > 0) {
       const restResults = await Promise.all(
         rest.map(async (model) => {
-          const result = await pingModelByKind(`${alias}/${model.id}`, model.type || "llm", baseUrl);
+          const result = await pingModelByKind(`${alias}/${model.id}`, model.kind || model.type || "llm", baseUrl);
           return { modelId: model.id, name: model.name || model.id, ...result };
         })
       );