feat: improve directory search with path completion and subdirectory listing

[huynle]

Summary

Improves the 'Open project' dialog search functionality to support direct path typing and dynamic subdirectory listing.

Changes

• Frontend: Transform search results to match user input format (~/... or absolute paths)
• Frontend: Add skipClientFilter prop to skip client-side fuzzy filtering for async searches
• Backend: Accept directory parameter and dynamically list subdirectories when typing paths
• Backend: Check disk for paths beyond pre-scanned depth

Problem Solved

Previously only scanned 2 levels deep from home. Now nested projects like ~/projects/hindsight/dev are discoverable by typing the path directly or browsing subdirectories.

Testing

• Typing ~/projects/hindsight shows directory and its subdirectories
• Typing ~/projects/hindsight/dev finds level 3+ directories
• Absolute paths work correctly