Add multilingual STT support and config UI/runtime updates

config.example.json

@@ -1,4 +1,5 @@
 {
+  "config_version": 1,
   "daemon": {
     "hotkey": "Cmd+m"
   },
@@ -6,8 +7,27 @@
     "input": ""
   },
   "stt": {
+    "provider": "local_whisper",
     "model": "base",
-    "device": "cpu"
+    "device": "cpu",
+    "language": "auto"
+  },
+  "llm": {
+    "provider": "local_llama"
+  },
+  "models": {
+    "allow_custom_models": false,
+    "whisper_model_path": "",
+    "llm_model_path": ""
+  },
+  "external_api": {
+    "enabled": false,
+    "provider": "openai",
+    "base_url": "https://api.openai.com/v1",
+    "model": "gpt-4o-mini",
+    "timeout_ms": 15000,
+    "max_retries": 2,
+    "api_key_env_var": "AMAN_EXTERNAL_API_KEY"
   },
   "injection": {
     "backend": "clipboard",