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>

backend/prisma/schema.prisma

@@ -102,7 +102,7 @@ model Flight {
 model Driver {
   id              String          @id @default(uuid())
   name            String
-  phone           String
+  phone           String?         // Optional - driver should add via profile
   department      Department?
   userId          String?         @unique
   user            User?           @relation(fields: [userId], references: [id])
@@ -114,6 +114,7 @@ model Driver {
 
   events          ScheduleEvent[]
   assignedVehicle Vehicle?        @relation("AssignedDriver")
+  messages        SignalMessage[] // Signal chat messages
 
   createdAt       DateTime        @default(now())
   updatedAt       DateTime        @updatedAt
@@ -198,6 +199,10 @@ model ScheduleEvent {
   // Metadata
   notes           String?     @db.Text
 
+  // Reminder tracking
+  reminder20MinSent Boolean   @default(false)
+  reminder5MinSent  Boolean   @default(false)
+
   createdAt       DateTime    @default(now())
   updatedAt       DateTime    @updatedAt
   deletedAt       DateTime?   // Soft delete
@@ -224,3 +229,77 @@ enum EventStatus {
   CANCELLED
 }
 
+// ============================================
+// Signal Messaging
+// ============================================
+
+model SignalMessage {
+  id              String           @id @default(uuid())
+  driverId        String
+  driver          Driver           @relation(fields: [driverId], references: [id], onDelete: Cascade)
+  direction       MessageDirection
+  content         String           @db.Text
+  timestamp       DateTime         @default(now())
+  isRead          Boolean          @default(false)
+  signalTimestamp String?          // Signal's message timestamp for deduplication
+
+  @@map("signal_messages")
+  @@index([driverId])
+  @@index([driverId, isRead])
+  @@index([timestamp])
+}
+
+enum MessageDirection {
+  INBOUND   // Message from driver
+  OUTBOUND  // Message to driver
+}
+
+// ============================================
+// PDF Settings (Singleton)
+// ============================================
+
+model PdfSettings {
+  id String @id @default(uuid())
+
+  // Branding
+  organizationName String  @default("VIP Coordinator")
+  logoUrl          String? @db.Text // Base64 data URL or external URL
+  accentColor      String  @default("#2c3e50") // Hex color
+  tagline          String?
+
+  // Contact Info
+  contactEmail          String  @default("contact@example.com")
+  contactPhone          String  @default("555-0100")
+  secondaryContactName  String?
+  secondaryContactPhone String?
+  contactLabel          String  @default("Questions or Changes?")
+
+  // Document Options
+  showDraftWatermark         Boolean  @default(false)
+  showConfidentialWatermark  Boolean  @default(false)
+  showTimestamp              Boolean  @default(true)
+  showAppUrl                 Boolean  @default(false)
+  pageSize                   PageSize @default(LETTER)
+
+  // Content Toggles
+  showFlightInfo        Boolean @default(true)
+  showDriverNames       Boolean @default(true)
+  showVehicleNames      Boolean @default(true)
+  showVipNotes          Boolean @default(true)
+  showEventDescriptions Boolean @default(true)
+
+  // Custom Text
+  headerMessage String? @db.Text
+  footerMessage String? @db.Text
+
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  @@map("pdf_settings")
+}
+
+enum PageSize {
+  LETTER
+  A4
+}
+