feat: orchestration harness, selective install, observer improvements

scripts/lib/install-targets/antigravity-project.js

@@ -0,0 +1,9 @@
+const { createInstallTargetAdapter } = require('./helpers');
+
+module.exports = createInstallTargetAdapter({
+  id: 'antigravity-project',
+  target: 'antigravity',
+  kind: 'project',
+  rootSegments: ['.agent'],
+  installStatePathSegments: ['ecc-install-state.json'],
+});