fix: Handle empty channel_idx parameter in messages filter

Fixed parse error when clicking the filter button on messages screen
with "All Channels" selected. The form was sending an empty string
for channel_idx, but FastAPI expected either a valid integer or None.

Changes:
- Accept channel_idx as string in query parameter
- Parse and validate channel_idx before passing to API
- Treat empty strings as None to prevent validation errors
- Add error handling for invalid integer values

Fixes #25

Co-authored-by: JingleManSweep <jinglemansweep@users.noreply.github.com>

src/meshcore_hub/web/routes/messages.py

@@ -15,7 +15,7 @@ router = APIRouter()
 async def messages_list(
     request: Request,
     message_type: str | None = Query(None, description="Filter by message type"),
-    channel_idx: int | None = Query(None, description="Filter by channel"),
+    channel_idx: str | None = Query(None, description="Filter by channel"),
     search: str | None = Query(None, description="Search in message text"),
     page: int = Query(1, ge=1, description="Page number"),
     limit: int = Query(50, ge=1, le=100, description="Items per page"),
@@ -28,12 +28,20 @@ async def messages_list(
     # Calculate offset
     offset = (page - 1) * limit
 
+    # Parse channel_idx, treating empty string as None
+    channel_idx_int: int | None = None
+    if channel_idx and channel_idx.strip():
+        try:
+            channel_idx_int = int(channel_idx)
+        except ValueError:
+            logger.warning(f"Invalid channel_idx value: {channel_idx}")
+
     # Build query params
     params: dict[str, int | str] = {"limit": limit, "offset": offset}
     if message_type:
         params["message_type"] = message_type
-    if channel_idx is not None:
-        params["channel_idx"] = channel_idx
+    if channel_idx_int is not None:
+        params["channel_idx"] = channel_idx_int
 
     # Fetch messages from API
     messages = []
@@ -62,7 +70,7 @@ async def messages_list(
             "limit": limit,
             "total_pages": total_pages,
             "message_type": message_type or "",
-            "channel_idx": channel_idx,
+            "channel_idx": channel_idx_int,
             "search": search or "",
         }
     )