docs: update API docs with cache/unregister endpoints and marcom training refs

docs/API_REFERENCE.md

@@ -14,6 +14,7 @@
 |------|------|------|--------|-----------|
 | V1.0 | 2026-03-18 | 創建文件 | Warren | OpenCode / MiniMax M2.5 |
 | V1.1 | 2026-03-23 | 更新端點與實際一致 | OpenCode | - |
+| V1.2 | 2026-03-25 | 新增快取/刪除 API | OpenCode | - |
 
 ---
 
@@ -384,6 +385,63 @@ curl http://localhost:3002/api/v1/videos
 
 ---
 
+## Cache Toggle
+
+Toggle caching at runtime.
+
+**Endpoint:** `POST /api/v1/config/cache`
+
+**Request Body:**
+```json
+{
+  "enabled": true
+}
+```
+
+| Field | Type | Required | Description |
+|-------|------|----------|-------------|
+| `enabled` | boolean | Yes | Enable (true) or disable (false) cache |
+
+**Response (200):**
+```json
+{
+  "cache_enabled": true,
+  "message": "Cache toggled successfully"
+}
+```
+
+---
+
+## Unregister Video
+
+Delete a video and all associated data (chunks, processor results, thumbnails).
+
+**Endpoint:** `POST /api/v1/unregister`
+
+**Request Body:**
+```json
+{
+  "uuid": "5dea6618a606e7c7"
+}
+```
+
+| Field | Type | Required | Description |
+|-------|------|----------|-------------|
+| `uuid` | string | Yes | Video UUID (16 character hex) |
+
+**Response (200):**
+```json
+{
+  "success": true,
+  "message": "Video unregistered successfully",
+  "uuid": "5dea6618a606e7c7"
+}
+```
+
+**Warning:** This operation is irreversible and will delete all associated chunks, processor results, and thumbnails.
+
+---
+
 ## Error Responses
 
 **400 Bad Request**
@@ -445,3 +503,5 @@ cargo run --bin momentry -- server --host 127.0.0.1 --port 3002
 | Search | `POST /api/v1/search` |
 | List videos | `GET /api/v1/videos` |
 | Lookup | `GET /api/v1/lookup?uuid=<uuid>` |
+| Toggle cache | `POST /api/v1/config/cache` |
+| Delete video | `POST /api/v1/unregister` |