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>

packages/coding-agent/docs/shell-aliases.md

@@ -0,0 +1,13 @@
+# Shell Aliases
+
+Pi runs bash in non-interactive mode (`bash -c`), which doesn't expand aliases by default.
+
+To enable your shell aliases, add to `~/.pi/agent/settings.json`:
+
+```json
+{
+  "shellCommandPrefix": "shopt -s expand_aliases\neval \"$(grep '^alias ' ~/.zshrc)\""
+}
+```
+
+Adjust the path (`~/.zshrc`, `~/.bashrc`, etc.) to match your shell config.