feat: add web dashboard UI for monitoring and managing cron jobs

[SimplicityGuy]

Summary

Add a comprehensive web-based dashboard that provides real-time monitoring and control of cron jobs. This addresses the need for visibility into job execution history, status tracking, and manual job triggering without requiring command-line access to the container.

Key Features

• Job monitoring with real-time status updates and health indicator
• Execution history with stdout/stderr log viewing
• Manual job triggering via web interface
• Dashboard statistics (total jobs, failures, recent activity)
• SQLite database for persistent execution tracking
• REST API for programmatic access
• Auto-refresh every 30 seconds with toast notifications

Technical Implementation

• Python Flask backend with vanilla JS frontend styled with Tailwind CSS
• Supervisord manages both crond and Flask processes
• Job scripts modified to log execution data to SQLite
• Custom cron parser (no external dependencies)
• Security: input validation, rate limiting, XSS prevention via safe DOM APIs (createElement/textContent)
• Merged with latest main — includes all bug fixes and dependency updates

Files Added/Modified

• webapp/ — Flask app, models, DB logger, cron parser, templates, JS frontend
• supervisord.conf — Process manager for crond + Flask
• Dockerfile — Added python3, py3-flask, py3-supervisor; sorted packages alphabetically
• entrypoint.sh — DB initialization, job sync, supervisord integration with atomic script generation
• docker-compose.yml — Port mapping (8080), data volume, environment variables
• scripts/update-project.sh — New update_webapp_packages() to verify webapp components
• .github/workflows/update-project.yml — Updated PR template to mention webapp packages

Test Plan

• docker-compose up — verify dashboard loads at localhost:8080
• Verify stats bar shows correct job counts
• Verify health indicator shows green "Healthy" status
• Click "Run Now" on a job — confirm toast notification and execution logged
• Click "History" — confirm execution history table renders
• Click "Logs" on an execution — confirm modal with stdout/stderr tabs
• Verify auto-refresh updates stats every 30 seconds
• Test responsive layout on mobile viewport
• Run ./scripts/update-project.sh --dry-run — verify webapp package checks pass

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