feat(FN-3332): add droid runtime plugin with event bridge and process manag

The merge delivers a new `fusion-plugin-droid-runtime` plugin providing a full MCP server and runtime adapter for droid-based agents, with event bridging, process management, tool mapping, and a prompt builder. It also adds agent delegation and org hierarchy tools to the pi extension, while fixing a

Fusion-Task-Id: FN-3332

packages/droid-cli/README.md

@@ -1,25 +1,8 @@
 # @fusion/droid-cli
 
-First-party Fusion pi extension package that routes pi provider requests through the `droid` CLI subprocess using stream-json NDJSON.
+Compatibility shim package for Fusion's Droid integration.
 
-## Provider
+Runtime/provider implementation now lives in:
+- `@fusion-plugin-examples/droid-runtime` (`plugins/fusion-plugin-droid-runtime`)
 
-- Provider ID: `droid-cli`
-- Binary: `droid` (must be installed and authenticated on PATH)
-- Registration: package extension entrypoint in `index.ts`
-
-## Capabilities
-
-- Subprocess streaming bridge for text/thinking/tool events
-- Model auto-discovery from Droid CLI at provider startup with in-process caching
-- Session resume support (`--resume` / `--session-id`) to avoid replaying prior turns
-- MCP schema bridge for exposing pi custom tools as schema-only definitions
-- Tool mapping and break-early control so pi remains the tool executor
-- Thinking effort mapping from pi reasoning options to Droid CLI flags
-
-## Development
-
-```bash
-pnpm --filter @fusion/droid-cli test
-pnpm --filter @fusion/droid-cli exec tsc --noEmit
-```
+This package preserves the historical pi extension entrypoint and delegates to the plugin-owned implementation so existing imports continue to work.