feat: implement multi-platform contest tracking with comprehensive notification system

- Implemented adapter pattern for platform abstraction
- Added support for 4 platforms: Codeforces, LeetCode, CodeChef, AtCoder
- Created unified ContestData format for cross-platform consistency
- Built platform registry with dependency injection for scalability

- Multi-channel support: Email, WhatsApp, Push notifications
- User preference-based notification delivery
- Contest reminder system with customizable timing
- Admin announcement and bulk email capabilities
- Notification history and retry mechanism
- Email templates with modern HTML design

- Refactored to adapter pattern following SOLID principles
- Implemented dependency injection throughout
- Created reusable base classes and interfaces
- Moved logger from core to common module
- Added role-based access control (RBAC)
- Enhanced security with public route decorator

- Complete CRUD operations for contests
- Advanced filtering: by platform, phase, difficulty, type
- Search functionality with pagination
- Contest statistics and analytics
- Automated contest synchronization (every 6 hours)
- Bulk operations support

- JWT-based authentication with refresh tokens
- Fixed refresh token bug (now correctly reuses refresh token)
- Role-based guards (Admin, User)
- Public route decorator for unprotected endpoints
- Enhanced user schema with notification preferences

- User activation/deactivation
- Profile management
- Role updates (Admin only)
- Notification channel preferences
- Custom notification timing (1-168 hours before contest)

- VitePress-based documentation site
- Comprehensive API documentation for all endpoints
- Backend architecture guides
- Platform adapter documentation
- Database schema documentation
- Security and deployment guides
- GitHub Pages deployment workflow

- PlatformsModule: Platform adapter registry and management
- NotificationsModule: Multi-channel notification system
- ContestSchedulerService: Automated contest sync and cleanup

- CodeforcesAdapter: REST API integration (enabled)
- LeetCodeAdapter: GraphQL API integration (enabled)
- CodeChefAdapter: REST API integration (enabled)
- AtCoderAdapter: Community API integration (enabled)

- Enhanced Contest schema with multi-platform support
- New Notification schema for tracking notification history
- Updated User schema with notification preferences

- EmailNotificationService: Nodemailer integration
- WhatsAppNotificationService: Twilio integration
- PushNotificationService: Web Push API integration
- AdminEmailService: Admin-specific email operations

- @nestjs/schedule: Cron job scheduling
- nodemailer: Email sending
- twilio: WhatsApp messaging
- web-push: Push notifications

- Deprecated alerts module (replaced by notifications)
- Old documentation structure (migrated to VitePress)
- Zod validation pipe (using class-validator)

- Removed /alerts endpoints (use /notifications instead)
- Changed contest sync from hourly to every 6 hours
- Updated user schema with new required fields

- Added comprehensive test specs for all new services
- Unit tests for adapters, guards, and decorators
- E2E test setup with UI test page

Author: Celestial-0

.github/workflows/deploy-docs.yml

@@ -0,0 +1,74 @@
+# Workflow for building and deploying CodeNotify Backend VitePress documentation to GitHub Pages
+name: Deploy CodeNotify Documentation
+
+on:
+  # Runs on pushes targeting the main branch
+  push:
+    branches: [main]
+    paths:
+      - 'docs/**'
+      - '.github/workflows/deploy-docs.yml'
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+# Allow only one concurrent deployment, skipping runs queued between the run in-progress and latest queued.
+# However, do NOT cancel in-progress runs as we want to allow these production deployments to complete.
+concurrency:
+  group: pages
+  cancel-in-progress: false
+
+jobs:
+  # Build job
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0 # Not needed if lastUpdated is not enabled
+
+      # - uses: pnpm/action-setup@v3 # Uncomment this if you're using pnpm
+      #   with:
+      #     version: 9
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+          cache-dependency-path: docs/package-lock.json
+
+      - name: Setup Pages
+        uses: actions/configure-pages@v4
+
+      - name: Install dependencies
+        run: npm ci
+        working-directory: docs
+
+      - name: Build with VitePress
+        run: npm run docs:build
+        working-directory: docs
+
+      - name: Upload artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: docs/.vitepress/dist
+
+  # Deployment job
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    needs: build
+    runs-on: ubuntu-latest
+    name: Deploy
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4