Make release and sidecar-release manual-only while testing

Removed push triggers from both coordinator workflows. They now
only run via workflow_dispatch (manual "Run workflow" button).
Re-enable push triggers once the build pipeline is stable.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/sidecar-release.yml

@@ -1,14 +1,6 @@
 name: Sidecar Release
 
 on:
-  push:
-    branches: [main]
-    paths:
-      - 'client/**'
-      - 'server/**'
-      - 'backend/**'
-      - 'pyproject.toml'
-      - 'local-transcription-headless.spec'
   workflow_dispatch:
 
 jobs: