chore: update install commands to use tag-based URLs (#200)

Changed install commands to download install.sh directly from the release
tag instead of from main branch with --tag parameter. This ensures:

1. The install script version matches the release being installed
2. No version mismatch between script and code
3. Simpler, cleaner install commands

Changes:
- install.sh: Updated error message to use v0.6.0-beta URL
- README.md: All install commands now use v0.6.0-beta/install.sh
- docs/INSTALL.md: Updated quick install command
- docs/UPDATE.md: Updated update command examples
- docs/RELEASE_PROCESS.md: Updated example command
- src/vocalinux/main.py: Updated error message install command
- tests/distro-testing-checklist.md: Updated download URL
- web/src/app/page.tsx: Now uses dynamic tag in URL (not main)
- .github/workflows/release.yml: Release notes use tag-based URL

Before:
  curl .../main/install.sh | bash -s -- --tag=v0.6.0-beta

After:
  curl .../v0.6.0-beta/install.sh | bash

Fixes version consistency between install script and installed code.

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/main/install.sh | bash -s -- --tag=v0.5.0-beta
+curl -fsSL https://raw.githubusercontent.com/jatinkrmalik/vocalinux/v0.6.0-beta/install.sh | bash
 ```
 
 **Release Announcement (lines ~31-34):**