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/handlers/ttsProviders/index.js

@@ -33,8 +33,10 @@ export async function synthesizeViaConfig(provider, text, model, credentials) {
   if (!handler) return null;
   const apiKey = credentials?.apiKey;
   if (cfg.authType !== "none" && !apiKey) throw new Error(`${provider} API key required`);
-  const defaultModel = cfg.models?.[0]?.id || "";
-  const { modelId, voiceId } = parseModelVoice(model, defaultModel, "", cfg.models || []);
+  const { PROVIDER_MODELS } = await import("open-sse/config/providerModels.js");
+  const ttsModels = (PROVIDER_MODELS[provider] || []).filter(m => (m.kind || m.type) === "tts");
+  const defaultModel = ttsModels[0]?.id || "";
+  const { modelId, voiceId } = parseModelVoice(model, defaultModel, "", ttsModels);
   return handler({ baseUrl: cfg.baseUrl, apiKey, text, modelId, voiceId });
 }