feat: US-003 - Creează catalogul de voci tts_voices.json cu seed inițial

- tts_voices.json (nou): seed 17 intrări — M1-M5/F1-F5 supertonic, Marius 1-3
  și Paula 1-3 pockettts (state_path spre models/voices/*.safetensors), alba
  pockettts (voice_url)
- .gitignore: +*.lock pentru sidecar-uri jsonlock
- elimină approved-tasks.json.lock din git (sidecar gol, jsonlock îl recreează)
- scris prin src/jsonlock.py write_locked()
- gates: /review (backend) PASS, db (schema manuală) PASS, pytest 1043 passed
  (22 eșecuri preexistente neschimbate)

tts_voices.json

@@ -0,0 +1,66 @@
+{
+  "M1": {
+    "engine": "supertonic"
+  },
+  "M2": {
+    "engine": "supertonic"
+  },
+  "M3": {
+    "engine": "supertonic"
+  },
+  "M4": {
+    "engine": "supertonic"
+  },
+  "M5": {
+    "engine": "supertonic"
+  },
+  "F1": {
+    "engine": "supertonic"
+  },
+  "F2": {
+    "engine": "supertonic"
+  },
+  "F3": {
+    "engine": "supertonic"
+  },
+  "F4": {
+    "engine": "supertonic"
+  },
+  "F5": {
+    "engine": "supertonic"
+  },
+  "Marius 1": {
+    "engine": "pockettts",
+    "state_path": "models/voices/marius-1.safetensors",
+    "owner": "Marius"
+  },
+  "Marius 2": {
+    "engine": "pockettts",
+    "state_path": "models/voices/marius-2.safetensors",
+    "owner": "Marius"
+  },
+  "Marius 3": {
+    "engine": "pockettts",
+    "state_path": "models/voices/marius-3.safetensors",
+    "owner": "Marius"
+  },
+  "Paula 1": {
+    "engine": "pockettts",
+    "state_path": "models/voices/paula-1.safetensors",
+    "owner": "Paula"
+  },
+  "Paula 2": {
+    "engine": "pockettts",
+    "state_path": "models/voices/paula-2.safetensors",
+    "owner": "Paula"
+  },
+  "Paula 3": {
+    "engine": "pockettts",
+    "state_path": "models/voices/paula-3.safetensors",
+    "owner": "Paula"
+  },
+  "alba": {
+    "engine": "pockettts",
+    "voice_url": "alba"
+  }
+}