v0.5.0 - Fast scanning + Rust CLI

Big performance and UX update.

Highlights:

• GUI launches instantly - scanning happens in background
• 2-4x faster scanning with parallel I/O
• New Rust CLI (dswp) for command-line power users

What's New:

• Parallel scanner using ThreadPoolExecutor
• Background scanning with progress indicator
• Rescan button for manual scans
• Rust CLI with JSON output and dry-run mode
• Better status messages

Fixes:

• CLI import isolation (prevents GUI deps leaking)

Full changelog: CHANGELOG.md