test(api): add Bruno tests for sync-kobo and OPDS features

Sync-Kobo:
- Auto link books endpoint tests
- Bulk link books endpoint tests
- Get unlinked book suggestions endpoint tests

OPDS:
- Download book with on-the-fly KEPUB conversion tests

All tests cover no user, user, and admin contexts

bruno/sync-kobo/Auto Link Books.bru

@@ -0,0 +1,24 @@
+{
+  "meta": {
+    "name": "Auto-Link Unlinked Books",
+    "type": "http"
+  },
+  "req": {
+    "url": "{{baseUrl}}/sync/auto-link-books",
+    "method": "POST",
+    "header": [
+      {
+        "key": "Content-Type",
+        "value": "application/json"
+      },
+      {
+        "key": "Authorization",
+        "value": "Bearer {{authToken}}"
+      }
+    ],
+    "body": {
+      "confidence_threshold": 0.8,
+      "limit": 50
+    }
+  }
+}