Feature/enhanced collaboration workflow

[Roshan1299]

📋 Pull Request Description

What does this PR do?

Implements the Enhanced Collaboration Workflow — users can apply to collaboration posts by swiping right, project owners can manage applicants via a dashboard, and accepted applicants automatically get a chat created with a welcome message. Also fixes chat UI bugs and unifies the side navigation drawer across tabs.

Related Issues

• Implements US 04.02.01 #63

📱 Platform(s) Affected

• Android
• Backend/API
• Web Interface
• Documentation
• CI/CD

🧪 Type of Changes

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 📚 Documentation update
• 🔧 Refactoring (no functional changes)
• ⚡ Performance improvement
• 🧹 Code cleanup
• 🔒 Security fix

📝 Detailed Changes

Key Changes Made:

• Swipe right on a collaboration post to apply; backend validates no self-apply, no duplicates, and post must be active (not filled)
• Owner Dashboard screen accessible from drawer — lists owner's posts with expandable applicant list, accept/decline buttons, and tappable profiles
• My Applications screen accessible from drawer — shows all user's applications with color-coded status badges (PENDING/ACCEPTED/DECLINED)
• On accept: auto-increments team size, auto-fills post when full, creates chat conversation with welcome message
• Unified side navigation drawer across Home and Collaborate tabs with consistent blue theme
• Chat UI hotfixes: back button, message bubble colors, timestamps, empty state

Technical Details:

• Backend: New CollabApplication JPA entity with unique constraint on (post, applicant). CollabApplicationService handles business logic. 5 new REST endpoints on CollabPostController.
• Frontend: 3 new adapters (ApplicantAdapter, OwnerPostAdapter, MyApplicationAdapter), 2 new fragments (OwnerDashboardFragment, MyApplicationsFragment), swipe-right apply logic in CollabCardStackManager. Navigation graph updated with new destinations and actions.

🧪 Testing

How Has This Been Tested?

• Unit tests
• Integration tests
• Manual testing
• Automated UI tests

Test Configuration:

• Device/OS: Physical Android device via ADB reverse
• App Version: debug build
• Test Data: Local PostgreSQL

Test Cases Covered:

• Happy path scenarios
• Edge cases
• Error handling
• Performance impact

📷 Screenshots/Videos

Before:

N/A — new feature

After:

📊 Performance Impact

• No performance impact
• Improves performance
• May impact performance (explain below)
• Performance impact unknown

🔐 Security Considerations

• No security implications
• Security review required
• Addresses security vulnerability

📋 Migration Notes

• No migration required
• Database migration required
• Configuration changes required
• Documentation updates required

Hibernate ddl-auto: update will auto-create the collab_applications table on next backend startup. No manual migration needed.

✅ Checklist

Code Quality

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added error handling where appropriate

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have tested this change on multiple devices/browsers (if applicable)

Documentation

• I have made corresponding changes to the documentation
• I have updated the changelog (if applicable)
• I have added inline code comments for complex logic

Dependencies

• I have not introduced any new dependencies without discussion
• All new dependencies are properly documented
• I have verified license compatibility for any new dependencies

🔗 Additional Notes

The adb reverse tcp:8080 tcp:8080 command must be re-run each time the physical device is reconnected. This is documented in docs/SETUP.md.

📞 Reviewer Instructions

• Pay special attention to CollabApplicationService.kt — handles accept/decline logic and auto-chat creation
• Test specifically on physical device with ADB reverse
• Review the logic in CollabCardStackManager.kt for swipe-right apply flow

---

For Maintainers:

• Version bump required
• Release notes updated
• Marketing team notified (for user-facing changes)