feat(export): implement CSV and Excel export for task data

[desireddymohithreddy0925]

Summary

Adds the ability to export task data to both CSV and Excel (.xlsx) formats directly from the dashboard, addressing requests for reporting and external stakeholder sharing.

Closes #2887

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that changes existing functionality)
• 📝 Documentation update
• 🎨 Code style update (formatting, renaming)
• ♻️ Refactoring (no functional changes)
• 🧪 Testing
• 🏗️ Build / CI/CD / Infrastructure

Description

This PR addresses issue #2887 by extending our tasks schema to support complex project management data and introducing a dual-format export widget.

Changes made:

• Database Schema Upgrades: Extended the tasks schema via migration to include status, priority, due_date, and tags columns. (Includes backward compatibility fallback for older completed boolean tasks).
• API Extension: Updated GET, POST, PUT on /api/tasks and /api/tasks/[id] to seamlessly manage and return the new data structures securely using RLS.
• TaskExportButton Component: Built a dedicated UI component capable of two operations:
  • CSV Export: Uses native browser blobs to generate cleanly formatted .csv reports with robust string escaping for task titles and tags.
  • Excel Export: Utilizes SheetJS (dynamically imported to preserve small initial bundle sizes) to generate formatted .xlsx workbooks.
• Dashboard Integration: Mounted the new export capabilities alongside the existing export workflows within DashboardPage.

Testing

• Confirmed database migration applied smoothly and legacy data is handled cleanly.
• Verified CSV payload is well-formed even if users include commas or quotes inside their Task Titles.
• Verified xlsx dynamic import successfully generates valid Excel files.
• Executed local static analysis (pnpm typecheck) flawlessly.

Screenshots / Screen Recording

(Attach a screenshot of the new Export buttons in the dashboard, or a snippet of the generated CSV file)

[github-actions]

GSSoC Label Checklist 🏷️

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