refactor: unify providers and models tables

- Rename `llm_providers` → `providers`, `llm_provider_oauth_tokens` → `provider_oauth_tokens`
- Remove `tts_providers` and `tts_models` tables; speech models now live in the unified `models` table with `type = 'speech'`
- Replace top-level `api_key`/`base_url` columns with a JSONB `config` field on `providers`
- Rename `llm_provider_id` → `provider_id` across all references
- Add `edge-speech` client type and `conf/providers/edge.yaml` default provider
- Create new read-only speech endpoints (`/speech-providers`, `/speech-models`) backed by filtered views of the unified tables
- Remove old TTS CRUD handlers; simplify speech page to read-only + test
- Update registry loader to skip malformed YAML files instead of failing entirely
- Fix YAML quoting for model names containing colons in openrouter.yaml
- Regenerate sqlc, swagger, and TypeScript SDK

db/migrations/0013_model_id_unique_per_provider.up.sql

@@ -1,5 +1,6 @@
 -- 0013_model_id_unique_per_provider
 -- Change model_id uniqueness from global to per provider.
+-- NOTE: On fresh databases the canonical schema already has the correct constraint.
 
 DO $$
 BEGIN
@@ -7,9 +8,12 @@ BEGIN
     ALTER TABLE models DROP CONSTRAINT models_model_id_unique;
   END IF;
 
-  IF NOT EXISTS (SELECT 1 FROM pg_constraint WHERE conname = 'models_provider_model_id_unique') THEN
-    ALTER TABLE models
-      ADD CONSTRAINT models_provider_model_id_unique UNIQUE (llm_provider_id, model_id);
+  IF NOT EXISTS (SELECT 1 FROM pg_constraint WHERE conname = 'models_provider_model_id_unique')
+     AND NOT EXISTS (SELECT 1 FROM pg_constraint WHERE conname = 'models_provider_id_model_id_unique') THEN
+    IF EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name = 'models' AND column_name = 'llm_provider_id') THEN
+      ALTER TABLE models
+        ADD CONSTRAINT models_provider_model_id_unique UNIQUE (llm_provider_id, model_id);
+    END IF;
   END IF;
 END
 $$;