feat: comprehensive update with Signal, Copilot, themes, and PDF features

## Signal Messaging Integration
- Added SignalService for sending messages to drivers via Signal
- SignalMessage model for tracking message history
- Driver chat modal for real-time messaging
- Send schedule via Signal (ICS + PDF attachments)

## AI Copilot
- Natural language interface for VIP Coordinator
- Capabilities: create VIPs, schedule events, assign drivers
- Help and guidance for users
- Floating copilot button in UI

## Theme System
- Dark/light/system theme support
- Color scheme selection (blue, green, purple, orange, red)
- ThemeContext for global state
- AppearanceMenu in header

## PDF Schedule Export
- VIPSchedulePDF component for schedule generation
- PDF settings (header, footer, branding)
- Preview PDF in browser
- Settings stored in database

## Database Migrations
- add_signal_messages: SignalMessage model
- add_pdf_settings: Settings model for PDF config
- add_reminder_tracking: lastReminderSent for events
- make_driver_phone_optional: phone field nullable

## Event Management
- Event status service for automated updates
- IN_PROGRESS/COMPLETED status tracking
- Reminder tracking for notifications

## UI/UX Improvements
- Driver schedule modal
- Improved My Schedule page
- Better error handling and loading states
- Responsive design improvements

## Other Changes
- AGENT_TEAM.md documentation
- Seed data improvements
- Ability factory updates
- Driver profile page

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/components/ThemeToggle.tsx

@@ -0,0 +1,65 @@
+import { useState, useRef, useEffect } from 'react';
+import { Sun, Moon, Monitor } from 'lucide-react';
+import { useTheme, ThemeMode } from '@/hooks/useTheme';
+
+const modes: { value: ThemeMode; label: string; icon: typeof Sun }[] = [
+  { value: 'light', label: 'Light', icon: Sun },
+  { value: 'dark', label: 'Dark', icon: Moon },
+  { value: 'system', label: 'System', icon: Monitor },
+];
+
+export function ThemeToggle() {
+  const { mode, resolvedTheme, setMode } = useTheme();
+  const [isOpen, setIsOpen] = useState(false);
+  const dropdownRef = useRef<HTMLDivElement>(null);
+
+  // Close dropdown when clicking outside
+  useEffect(() => {
+    function handleClickOutside(event: MouseEvent) {
+      if (dropdownRef.current && !dropdownRef.current.contains(event.target as Node)) {
+        setIsOpen(false);
+      }
+    }
+    document.addEventListener('mousedown', handleClickOutside);
+    return () => document.removeEventListener('mousedown', handleClickOutside);
+  }, []);
+
+  // Get current icon based on resolved theme
+  const CurrentIcon = resolvedTheme === 'dark' ? Moon : Sun;
+
+  return (
+    <div className="relative" ref={dropdownRef}>
+      <button
+        onClick={() => setIsOpen(!isOpen)}
+        className="flex items-center justify-center w-9 h-9 rounded-lg bg-muted hover:bg-accent transition-colors focus-ring"
+        aria-label={`Current theme: ${mode}. Click to change.`}
+        aria-expanded={isOpen}
+        aria-haspopup="true"
+      >
+        <CurrentIcon className="h-5 w-5 text-foreground" />
+      </button>
+
+      {isOpen && (
+        <div className="absolute right-0 mt-2 w-36 rounded-lg bg-popover border border-border shadow-elevated z-50 overflow-hidden animate-in fade-in slide-in-from-top-2 duration-150">
+          {modes.map(({ value, label, icon: Icon }) => (
+            <button
+              key={value}
+              onClick={() => {
+                setMode(value);
+                setIsOpen(false);
+              }}
+              className={`flex items-center gap-3 w-full px-3 py-2.5 text-sm transition-colors ${
+                mode === value
+                  ? 'bg-primary/10 text-primary font-medium'
+                  : 'text-popover-foreground hover:bg-accent'
+              }`}
+            >
+              <Icon className="h-4 w-4" />
+              {label}
+            </button>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}