Phase 3 Week 7: Add KOReader routes, tests, and documentation

- Add KOReader sync endpoints to main application router
- Create Bruno API collection for testing KOReader endpoints
- Add integration tests for KOReader functionality
- Include comprehensive README with setup instructions
- Test coverage for progress, metadata, library, and bookmarks sync
- Part of Phase 3 KOReader Integration implementation

bruno/koreader/Get Library.bru

@@ -0,0 +1,19 @@
+meta {
+  name: KOReader Get Library
+  type: http
+  seq: 3
+}
+
+get {
+  url: {{baseUrl}}/api/sync/koreader/library
+  headers: {
+    Authorization: Bearer {{device_token}},
+    Content-Type: application/json
+  }
+}
+
+assert {
+  res.status == 200
+  res.body.library_sync != null
+  res.body.total_books >= 0
+}