feat: add conversation title editing functionality

[Aayushgoyal00]

Description

This PR implements a conversation rename feature that allows users to customize their conversation titles for better organization. The feature supports multiple interaction methods (double-click, edit icon, long-press) and provides immediate visual feedback with persistent storage.

Fixes #76

Key Features:

• Click pencil icon to rename any conversation
• Double-tap conversation title to edit (desktop)
• Long-press for mobile editing
• Inline editing with save/cancel buttons
• Persistent storage in database
• Real-time sync across devices
• Consistent UI with app theme

Technical Changes:

• Modified conversations table to use title field directly instead of nested metadata
• Updated chat-history.tsx with editing state management
• Enhanced useChatHistoryData hook to properly handle title updates
• Added updateConversationTitle service function
• Improved display logic to prioritize custom titles over auto-generated ones

Type of Change

• 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 not work as expected)
• Documentation update
• Release (version bump)

Release

Is this a release? No

Testing

Manual Testing Completed:

• Tested renaming conversations via pencil icon click
• Verified double-tap functionality on desktop
• Confirmed titles persist after page refresh
• Validated real-time sync between multiple sessions
• Tested edge cases (empty titles, special characters)
• Verified no impact on existing conversations
• Checked that renamed titles appear correctly in chat history

Automated Testing:

• Existing unit tests pass without modification
• Integration tests require test environment setup (TEST_SUPABASE credentials)
• Note: Changes don't affect existing test coverage, feature is additive

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings or errors
• I have added tests that prove my fix is effective or that my feature works (Manual testing completed, automated tests pending environment setup)
• New and existing tests pass locally with my changes (unit tests pass, integration tests require environment setup)
• If releasing, I have verified the version number is correct and follows semantic versioning

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[edgarpavlovsky]

1. related UI conversation: feat: Added Delete Conversation feature #96 (comment)

2. the AI is actually supposed to automatically update conversation names when conversations get started but there's a bug - could we tackle fixing that in this PR as well? would be more impactful