feat(FN-3328): refactor droid-cli into compatibility shim backed by fusion-

Merged FN-3328: Refactored the droid integration by converting `droid-cli` into a lightweight compatibility shim that delegates to `fusion-plugin-droid-runtime`, reducing droid-cli by ~5,400 lines of code while moving the actual runtime logic into the plugin scaffold. Updated the plugin loader to al

Fusion-Task-Id: FN-3328

plugins/fusion-plugin-droid-runtime/README.md

@@ -1,19 +1,38 @@
 # Droid Runtime Plugin
 
-First-class Droid plugin package under `plugins/fusion-plugin-droid-runtime`.
+First-class Droid runtime/provider plugin (`@fusion-plugin-examples/droid-runtime`).
 
-## What this package is
+## Purpose
 
-- Canonical home for Droid runtime/provider plugin code.
-- Installable from dashboard **Settings → Plugins → Fusion Plugins → Bundled Plugins** via path `./plugins/fusion-plugin-droid-runtime`.
-- Plugin identity is stable: `fusion-plugin-droid-runtime`.
+This package is the canonical home for Droid-specific runtime behavior, including:
+- provider id `droid-cli`
+- model discovery + normalization
+- CLI subprocess streaming + session resume
+- MCP tool bridge + thinking effort mapping
+- probe contract via `probeDroidBinary`
 
-## Migration context
-
-- FN-3261 established this package as the official landing zone so Droid plugin work does not need ad-hoc layouts.
-- Runtime/provider logic that used to live in `packages/droid-cli` is now owned here; `@fusion/droid-cli` remains a compatibility shim surface where needed.
-
-## Key IDs
+## Runtime + Provider
 
 - Runtime ID: `droid`
-- Provider ID: `droid-cli`
+- Display name: `Droid Runtime`
+- Provider surface preserved: `Factory AI — via Droid CLI` (`droid-cli`)
+
+Core implementation files live in `src/`:
+- `runtime-adapter.ts`
+- `provider.ts`
+- `process-manager.ts`
+- `probe.ts`
+- prompt/tool/thinking/control helpers
+
+## Dashboard UI contribution surfaces
+
+The plugin registers `uiSlots` for:
+- `settings-provider-card`
+- `settings-integration-card`
+- `onboarding-provider-card`
+- `onboarding-setup-help`
+- `post-onboarding-recommendation`
+
+## Compatibility with `@fusion/droid-cli`
+
+`packages/droid-cli` is now a thin compatibility shim. It keeps the historical pi-extension entrypoint, but delegates runtime/provider behavior to this plugin package.