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/evil_mode.py

@@ -1,6 +1,7 @@
 """Evil mode routes."""
 
 from fastapi import APIRouter
+from fastapi.responses import JSONResponse
 import globals
 from routes.models import EvilMoodSetRequest
 from utils.logger import get_logger
@@ -43,7 +44,7 @@ def enable_evil_mode():
         globals.client.loop.create_task(apply_evil_mode_changes(globals.client))
         return {"status": "ok", "message": "Evil mode enabled", "evil_mode": True}
     else:
-        return {"status": "error", "message": "Discord client not ready"}
+        return JSONResponse(status_code=503, content={"status": "error", "message": "Discord client not ready"})
 
 
 @router.post("/evil-mode/disable")
@@ -58,7 +59,7 @@ def disable_evil_mode():
         globals.client.loop.create_task(revert_evil_mode_changes(globals.client))
         return {"status": "ok", "message": "Evil mode disabled", "evil_mode": False}
     else:
-        return {"status": "error", "message": "Discord client not ready"}
+        return JSONResponse(status_code=503, content={"status": "error", "message": "Discord client not ready"})
 
 
 @router.post("/evil-mode/toggle")
@@ -67,7 +68,7 @@ def toggle_evil_mode():
     from utils.evil_mode import apply_evil_mode_changes, revert_evil_mode_changes
 
     if not globals.client or not globals.client.loop or not globals.client.loop.is_running():
-        return {"status": "error", "message": "Discord client not ready"}
+        return JSONResponse(status_code=503, content={"status": "error", "message": "Discord client not ready"})
 
     if globals.EVIL_MODE:
         globals.client.loop.create_task(revert_evil_mode_changes(globals.client))
@@ -95,10 +96,10 @@ def set_evil_mood_endpoint(data: EvilMoodSetRequest):
     from utils.evil_mode import set_evil_mood, is_valid_evil_mood, update_all_evil_nicknames
 
     if not is_valid_evil_mood(data.mood):
-        return {
+        return JSONResponse(status_code=400, content={
             "status": "error",
             "message": f"Mood '{data.mood}' not recognized. Available evil moods: {', '.join(globals.EVIL_AVAILABLE_MOODS)}"
-        }
+        })
 
     success = set_evil_mood(data.mood)
     if success:
@@ -107,4 +108,4 @@ def set_evil_mood_endpoint(data: EvilMoodSetRequest):
             globals.client.loop.create_task(update_all_evil_nicknames(globals.client))
         return {"status": "ok", "new_mood": data.mood}
 
-    return {"status": "error", "message": "Failed to set evil mood"}
+    return JSONResponse(status_code=500, content={"status": "error", "message": "Failed to set evil mood"})