move pi-mono into companion-cloud as apps/companion-os

- Copy all pi-mono source into apps/companion-os/
- Update Dockerfile to COPY pre-built binary instead of downloading from GitHub Releases
- Update deploy-staging.yml to build pi from source (bun compile) before Docker build
- Add apps/companion-os/** to path triggers
- No more cross-repo dispatch needed

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,38 @@
+node_modules/
+dist/
+*.log
+.DS_Store
+*.tsbuildinfo
+# packages/*/node_modules/
+packages/*/dist/
+packages/*/dist-chrome/
+packages/*/dist-firefox/
+
+# Environment
+.env
+
+# Editor files
+.vscode/
+.zed/
+.idea/
+*.swp
+*.swo
+*~
+
+# Package specific
+.npm/
+coverage/
+.nyc_output/
+.pi_config/
+tui-debug.log
+compaction-results/
+.opencode/
+syntax.jsonl
+out.jsonl
+pi-*.html
+out.html
+packages/coding-agent/binaries/
+todo.md
+
+# Riptide artifacts (cloud-synced)
+.humanlayer/tasks/