feat: implement client-side image resizing for avatar uploads

- Add resizeImage function to SettingsPage
- Resize images larger than 2MB to max 800x800 pixels
- Convert to JPEG with 80% quality to reduce file size
- Add server-side validation for 10MB file size limit
- Maintain aspect ratio during resizing
- Log resizing details for debugging

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

api/src/rehearsalhub/routers/auth.py

@@ -83,7 +83,7 @@ async def upload_avatar(
     print(f"Avatar upload called for member {current_member.id}")
     print(f"File: {file.filename}, Content-Type: {file.content_type}")
     
-    # Validate file type and size
+    # Validate file type
     if not file.content_type.startswith("image/"):
         print("Invalid file type")
         raise HTTPException(
@@ -91,6 +91,15 @@ async def upload_avatar(
             detail="Only image files are allowed"
         )
     
+    # Validate file size (10MB limit)
+    max_size = 10 * 1024 * 1024  # 10MB
+    if file.size > max_size:
+        print(f"File too large: {file.size} bytes (max {max_size})")
+        raise HTTPException(
+            status_code=status.HTTP_413_REQUEST_ENTITY_TOO_LARGE,
+            detail=f"File too large. Maximum size is {max_size / 1024 / 1024}MB"
+        )
+    
     # Create uploads directory if it doesn't exist
     upload_dir = "uploads/avatars"
     os.makedirs(upload_dir, exist_ok=True)