ThemeDeck v3.0.1

Fixes

• Fixes the auto-assign missing game tracks feature reporting zero games when Steam's frontend library cache is unavailable or empty.
• Adds a backend Steam library scan using the Deck's local Steam files so all/installed/uninstalled/missing-game bulk actions can find the real library.

Verification

• Confirmed on Steam Deck that ThemeDeck now detects the game library correctly.
• Built with pnpm build.
• Validated backend syntax with python3 -m py_compile main.py.