fix: GitHub Actions workflows now use GITHUB_TOKEN for dependencies

Fixed 4 failing workflow checks:

1. **Build/Lint/Test workflows**: Fixed yarn install authentication
   - Changed Git URL rewrite to include GITHUB_TOKEN in all rewrites
   - Added GITHUB_TOKEN and GIT_TERMINAL_PROMPT env vars to yarn install step
   - Now correctly handles github: dependencies (like libsignal)

2. **PR Comment workflow**: Fixed missing token error
   - Changed from secrets.PERSONAL_TOKEN to secrets.GITHUB_TOKEN
   - Workflow now has proper authentication

Root cause: Yarn 4.x was trying to clone github: dependencies via SSH,
but CI had no SSH keys. Git config now rewrites ALL GitHub URLs to
HTTPS with token authentication.

https://claude.ai/code/session_015R3U3kiprQiNTTNNt31Sg6

.github/workflows/pr-comment.yml

@@ -18,7 +18,7 @@ jobs:
 
       - uses: mshick/add-pr-comment@v2
         with:
-          repo-token: ${{ secrets.PERSONAL_TOKEN }}
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
           message-id: pr-test
           message: |
             Thanks for opening this pull request and contributing to the project!