Change workflow to manual trigger only

Remove automatic triggers on push/PR to avoid slow builds running
unexpectedly. Use workflow_dispatch for manual control.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/workflows/build-test.yml

@@ -1,11 +1,7 @@
 name: Build and Test
 
 on:
-  push:
-    branches: [main]
-  pull_request:
-    branches: [main]
-  workflow_dispatch:
+  workflow_dispatch:  # Manual trigger only
 
 env:
   TESTLINK_URL: http://localhost:8090