## Docs: add Forget Matching endpoint + fix stale Forget Memory docs
### What this does
- **Adds docs for the new** **`POST /v4/memories/forget-matching`** **endpoint** — semantic/promptable mass-forget. Covers `dryRun` (preview), `threshold`/`maxForget` safety bounds, the request/response shape, and `forgetBatchId`.
- **Corrects the existing "Forget Memory" section** to match the actual implementation.
### ⚠️ No API surface changed
This PR is **docs-only**. The existing forget endpoint's behavior/contract is untouched — the previous docs were simply **wrong** and described a route that has never existed:
| | Old docs (incorrect) | Actual implementation (unchanged) |
| --- | --- | --- |
| Method + path | `POST /v4/memories/{id}/forget` | `DELETE /v4/memories` |
| Body | — | `{ id \| content, containerTag, reason? }` |
The handler (`forgetMemory` in `apps/api/src/routes/v4/memories/handlers.ts`) was not modified — this just makes the docs reflect reality.
### Also
- Small accuracy cleanups (response field descriptions, realistic example IDs).
1af9dbc448
