fix: download install.sh from main to get --tag support (#78)

The v0.3.0-alpha release was created before the --tag feature was
added to install.sh, so installing from that tag fails with "Unknown
option: --tag=v0.3.0-alpha".

Solution: Always download install.sh from main (which has --tag support)
and pass the release tag as a parameter. This ensures users get a working
installer that can install the specific stable release.

Changes:
- web/src/app/page.tsx: Download from main instead of ${latestRelease}
- README.md: Update install commands to download from main
- docs/INSTALL.md: Update install command
- .github/workflows/release.yml: Update release notes

.github/workflows/release.yml

@@ -74,7 +74,7 @@ jobs:
 
             ### Quick Install (Recommended)
             ```bash
-            curl -fsSL https://raw.githubusercontent.com/jatinkrmalik/vocalinux/${{ github.ref_name }}/install.sh | bash
+            curl -fsSL https://raw.githubusercontent.com/jatinkrmalik/vocalinux/main/install.sh | bash -s -- --tag=${{ github.ref_name }}
             ```
 
             ### From Source