feat(pi): add native pi integration — extension, config pi, skills --agent pi

- src/pi-ext/: self-contained pi extension (mcpctl-pi.ts + vendored
  mcp-http client) that talks JSON-RPC directly to mcplocal and registers
  project MCP tools as native pi tools. No MCP client, no ~/.claude.
- Persistent per-project session so gated projects ungate on begin_session.
- /mcpctl command: status, switch project (GUI), refresh tools, sync skills.
- mcpctl config pi: installs extension, wires pi settings, persists active
  project, syncs skills into ~/.pi/agent/skills.
- skills sync: add --agent pi (target install root).
- docs + tests.

README.md

@@ -113,6 +113,30 @@ This writes a `.mcp.json` that tells Claude Code to connect through mcplocal. Re
 mcpctl console monitoring   # Preview what Claude sees
 ```
 
+### 7. Use mcpctl with pi (no MCP client, no Claude)
+
+[pi](https://github.com/earendil-works/pi) does not support MCP, but it supports
+**extensions** and **skills**. mcpctl ships a native pi integration that talks
+JSON-RPC directly to mcplocal over HTTP — no MCP library, no `~/.claude`
+dependency, so it keeps working even if you drop Claude entirely.
+
+```bash
+mcpctl config pi --project monitoring
+```
+
+This installs the `mcpctl` pi extension into `~/.pi/agent/extensions/mcpctl/`,
+registers it (plus a pi skills dir) in `~/.pi/agent/settings.json`, persists the
+active project in `~/.mcpctl/pi-state.json`, and runs an initial skills sync into
+`~/.pi/agent/skills/`. Then start pi and the project's MCP tools are registered as
+native pi tools (`mc_<project>_<tool>`).
+
+Inside pi:
+
+- `/mcpctl` — status, **switch project** (from the GUI), refresh tools, sync skills
+- gated projects auto-ungate: call `begin_session` once and the full tool set opens
+
+See [docs/pi-extension.md](docs/pi-extension.md) for full details.
+
 ## Declarative Configuration
 
 Everything can be defined in YAML and applied with `mcpctl apply`: