Adds a general-purpose External Annotations API that allows external programs (linters, AI tools, security scanners) to push annotations into a live Plannotator session via HTTP, with real-time delivery over SSE.
## What's included
- **Shared core** (`packages/shared/external-annotation.ts`): types, in-memory store, input validation, SSE serialization
- **Server handlers**: Bun + Pi implementations with full CRUD (GET/POST/PATCH/DELETE) + SSE streaming
- **Client hook** (`useExternalAnnotations`): EventSource with polling fallback, optimistic updates
- **Editor integration**: two-array state model (local + external), content-aware dedup, ID-based routing
- **Persistence**: source field preserved through share URLs and crash-recovery drafts
- **Docs**: new Integrations category with API overview page, updated API reference
## API surface
All three servers (plan, review, annotate) expose:
- `GET /api/external-annotations/stream` - SSE stream
- `GET /api/external-annotations` - JSON snapshot (polling fallback)
- `POST /api/external-annotations` - Add annotations (single or batch)
- `PATCH /api/external-annotations?id=` - Update fields
- `DELETE /api/external-annotations` - Remove by id, source, or clear all
For provenance purposes, this commit was AI assisted.
Michael Ramos