feat(coding-agent): add user_bash event and theme API extensions

- user_bash event for intercepting ! and !! commands (#528)
- Extensions can return { operations } or { result } to redirect/replace
- executeBashWithOperations() for custom BashOperations execution
- session.recordBashResult() for extensions handling bash themselves
- Theme API: getAllThemes(), getTheme(), setTheme() on ctx.ui
- mac-system-theme.ts example: sync with macOS dark/light mode
- Updated ssh.ts to use user_bash event

packages/coding-agent/CHANGELOG.md

@@ -8,8 +8,10 @@
 
 ### Added
 
+- `ctx.ui.getAllThemes()`, `ctx.ui.getTheme(name)`, and `ctx.ui.setTheme(name | Theme)` methods for extensions to list, load, and switch themes at runtime ([#576](https://github.com/badlogic/pi-mono/pull/576))
 - `--no-tools` flag to disable all built-in tools, allowing extension-only tool setups ([#557](https://github.com/badlogic/pi-mono/pull/557) by [@cv](https://github.com/cv))
 - Pluggable operations for built-in tools enabling remote execution via SSH or other transports ([#564](https://github.com/badlogic/pi-mono/issues/564)). Interfaces: `ReadOperations`, `WriteOperations`, `EditOperations`, `BashOperations`, `LsOperations`, `GrepOperations`, `FindOperations`
+- `user_bash` event for intercepting user `!`/`!!` commands, allowing extensions to redirect to remote systems ([#528](https://github.com/badlogic/pi-mono/issues/528))
 - `setActiveTools()` in ExtensionAPI for dynamic tool management
 - Built-in renderers used automatically for tool overrides without custom `renderCall`/`renderResult`
 - `ssh.ts` example: remote tool execution via `--ssh user@host:/path`