feat: add proper HTTP status codes to all API error responses

- 217 error returns across 18 route files + api.py now use JSONResponse
  with appropriate HTTP status codes instead of returning HTTP 200
- Status code distribution: 500 (121), 400 (39), 503 (28), 404 (24), 409 (3), 502 (2)
- Fixed language.py tuple-return bug (was serializing as JSON array)
- Fixed bare except clauses in bipolar_mode.py and voice.py
- Body-level error schemas preserved (status/error + success/error patterns)
  so web UI continues working without changes
- chat.py (SSE) unchanged: errors sent within stream protocol
- All 170 tests pass

bot/routes/config.py

@@ -1,6 +1,7 @@
 """Configuration management routes: get/set/reset/validate config."""
 
 from fastapi import APIRouter, Request
+from fastapi.responses import JSONResponse
 import globals
 from utils.logger import get_logger
 
@@ -24,7 +25,7 @@ async def get_full_config():
         }
     except Exception as e:
         logger.error(f"Failed to get config: {e}")
-        return {"success": False, "error": str(e)}
+        return JSONResponse(status_code=500, content={"success": False, "error": str(e)})
 
 
 @router.get("/config/static")
@@ -41,7 +42,7 @@ async def get_static_config():
         }
     except Exception as e:
         logger.error(f"Failed to get static config: {e}")
-        return {"success": False, "error": str(e)}
+        return JSONResponse(status_code=500, content={"success": False, "error": str(e)})
 
 
 @router.get("/config/runtime")
@@ -59,7 +60,7 @@ async def get_runtime_config():
         }
     except Exception as e:
         logger.error(f"Failed to get runtime config: {e}")
-        return {"success": False, "error": str(e)}
+        return JSONResponse(status_code=500, content={"success": False, "error": str(e)})
 
 
 @router.post("/config/set")
@@ -80,7 +81,7 @@ async def set_config_value(request: Request):
         persist = data.get("persist", True)
 
         if not key_path:
-            return {"success": False, "error": "key_path is required"}
+            return JSONResponse(status_code=400, content={"success": False, "error": "key_path is required"})
 
         from config_manager import config_manager
         config_manager.set(key_path, value, persist=persist)
@@ -114,7 +115,7 @@ async def set_config_value(request: Request):
         }
     except Exception as e:
         logger.error(f"Failed to set config: {e}")
-        return {"success": False, "error": str(e)}
+        return JSONResponse(status_code=500, content={"success": False, "error": str(e)})
 
 
 @router.post("/config/reset")
@@ -143,7 +144,7 @@ async def reset_config(request: Request):
         }
     except Exception as e:
         logger.error(f"Failed to reset config: {e}")
-        return {"success": False, "error": str(e)}
+        return JSONResponse(status_code=500, content={"success": False, "error": str(e)})
 
 
 @router.post("/config/validate")
@@ -163,7 +164,7 @@ async def validate_config_endpoint():
         }
     except Exception as e:
         logger.error(f"Failed to validate config: {e}")
-        return {"success": False, "error": str(e)}
+        return JSONResponse(status_code=500, content={"success": False, "error": str(e)})
 
 
 @router.get("/config/state")
@@ -180,4 +181,4 @@ async def get_config_state():
         }
     except Exception as e:
         logger.error(f"Failed to get config state: {e}")
-        return {"success": False, "error": str(e)}
+        return JSONResponse(status_code=500, content={"success": False, "error": str(e)})