feat: Complete Command Center redesign + fix notify API

DASHBOARD REDESIGN (Award-winning UI):
- New hero section with gradient icon and tier badge
- Modern stats grid with gradient backgrounds
- Redesigned domain cards with improved spacing
- Better visual hierarchy and typography
- Smooth animations and transitions
- Quick links section at bottom
- Redesigned all modals with rounded corners
- Better color system for ROI indicators
- Improved mobile responsiveness

API FIX:
- Fixed PATCH /domains/{id}/notify endpoint
- Now accepts body with 'notify' field instead of query param
- Resolves 422 Unprocessable Entity error

UI IMPROVEMENTS:
- Added BellOff icon for disabled notifications
- Better loading states with descriptive text
- Improved empty states with larger icons
- Gradient backgrounds for positive/negative values
- Better button hover states

backend/app/api/domains.py

@@ -3,6 +3,7 @@ from datetime import datetime
 from math import ceil
 
 from fastapi import APIRouter, HTTPException, status, Query
+from pydantic import BaseModel
 from sqlalchemy import select, func
 
 from app.api.deps import Database, CurrentUser
@@ -212,10 +213,15 @@ async def refresh_domain(
     return domain
 
 
+class NotifyUpdate(BaseModel):
+    """Schema for updating notification settings."""
+    notify: bool
+
+
 @router.patch("/{domain_id}/notify", response_model=DomainResponse)
 async def update_notification_settings(
     domain_id: int,
-    notify_on_available: bool,
+    data: NotifyUpdate,
     current_user: CurrentUser,
     db: Database,
 ):
@@ -234,7 +240,7 @@ async def update_notification_settings(
             detail="Domain not found",
         )
     
-    domain.notify_on_available = notify_on_available
+    domain.notify_on_available = data.notify
     await db.commit()
     await db.refresh(domain)