feat(launcher): bake Gitea base_url/owner/repo into pack from env or channel file

- inject-release-channel.js merges GITEA_* (or fractured-release-channel.json) into
  default-launcher.json before electron-builder.
- CI passes existing GITEA_BASE_URL/OWNER/REPO secrets into the Windows pack job.
- npm run pack:win/publish:win run the injector; workflows use npm run pack:win.

Co-authored-by: Cursor <cursoragent@cursor.com>

.github/workflows/gitea-release-sync.yml

@@ -74,11 +74,15 @@ jobs:
 
       - name: Install and pack (NSIS + portable)
         working-directory: tools/fractured-launcher-electron
+        env:
+          # Same values as upload step — baked into default-launcher.json (no token).
+          GITEA_BASE_URL: ${{ secrets.GITEA_BASE_URL }}
+          GITEA_OWNER: ${{ secrets.GITEA_OWNER }}
+          GITEA_REPO: ${{ secrets.GITEA_REPO }}
         run: |
           npm ci
-          # --publish never: on tagged checkouts electron-builder otherwise tries to
-          # push to GitHub releases and fails without GH_TOKEN (we upload via Gitea).
-          npx electron-builder --win nsis portable --x64 --publish never
+          # pack:win runs inject-release-channel.js then electron-builder --publish never
+          npm run pack:win
 
       - name: Stage launcher files for upload
         shell: pwsh