docs(api): add KOReader sync protocol documentation

- sync_progress.md - POST /api/sync/koreader/progress
- get_metadata.md - GET /api/sync/koreader/metadata/:uuid
- get_library.md - GET /api/sync/koreader/library
- sync_bookmarks.md - POST /api/sync/koreader/bookmarks

KOReader device sync endpoints with device authentication
for progress, metadata, library, and bookmarks

docs/developer/api/conflicts/dismiss_all_resolved.md

@@ -0,0 +1,38 @@
+# Dismiss All Resolved
+
+Dismiss all resolved conflicts.
+
+**Endpoint**: `POST /api/conflicts/dismiss-all`
+**Auth**: Required
+
+## Request Headers
+
+| Header | Type | Required | Description |
+|--------|------|-----------|-------------|
+| Authorization | string | Yes | Bearer token |
+
+### Example Request
+
+```http
+POST /api/conflicts/dismiss-all
+Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
+```
+
+## Response (200 OK)
+
+```json
+{
+  "message": "All resolved conflicts dismissed",
+  "count": 15
+}
+```
+
+## Error Responses
+
+| Code | Description |
+|------|-------------|
+| 401 | Invalid or expired token |
+
+## Try It Out
+
+<!-- API Explorer will be inserted here in Phase 3 -->