chore(release): prepare v0.6.1-beta (#201)

Bump version from 0.6.0-beta to 0.6.1-beta with installation improvements:

Version Updates:
- src/vocalinux/version.py: 0.6.0-beta → 0.6.1-beta
- install.sh: Default tag and help text updated
- web/package.json: 0.6.0 → 0.6.1
- web/src/app/layout.tsx: schema.org softwareVersion updated
- web/src/app/page.tsx: version badge updated

Documentation Updates:
- README.md: New 'What's New' section for v0.6.1-beta
- docs/UPDATE.md: Added v0.6.1-beta release notes with new features
- docs/INSTALL.md: Version references updated
- docs/RELEASE_PROCESS.md: Example commands updated
- tests/distro-testing-checklist.md: Version references updated
- src/vocalinux/main.py: Error message updated

New Features in v0.6.1-beta:
- Interactive backend selection for whisper.cpp (GPU vs CPU)
- Enhanced welcome message with testing instructions
- Simplified install commands (tag-based URLs)
- Better GPU support with proper library detection

Bug Fixes:
- Fixed bash arithmetic with set -e
- Fixed TTY detection for interactive mode
- Auto-install git if missing
- Fixed GPU installation commands

docs/RELEASE_PROCESS.md

@@ -112,7 +112,7 @@ Change the Development Status classifier:
 **Install Commands:**
 Update all curl commands to use the new tag:
 ```bash
-curl -fsSL https://raw.githubusercontent.com/jatinkrmalik/vocalinux/v0.6.0-beta/install.sh | bash
+curl -fsSL https://raw.githubusercontent.com/jatinkrmalik/vocalinux/v0.6.1-beta/install.sh | bash
 ```
 
 **Release Announcement (lines ~31-34):**