test(api): add Bruno tests for analytics, books, and bulk operations

Analytics:
- Reading stats endpoint tests
- Device usage tests
- Popular books tests

Books:
- Bulk delete tests
- Bulk update tests

Collections:
- Bulk add books to collections tests

Conflicts:
- Bulk resolve conflicts tests
- Bulk dismiss conflicts tests
- Bulk resolve highest progress tests

All tests cover no user, user, and admin contexts

bruno/collections/Bulk Add Books to Collections.bru

@@ -0,0 +1,49 @@
+{
+  "meta": {
+    "name": "Bulk Add Books to Collections",
+    "type": "http",
+    "event": [
+      {
+        "listen": "test",
+        "script": {
+          "exec": [
+            "// Test bulk add to collections response",
+            "if (response.status === 200) {",
+            "    tests['Bulk add successful'] = true;",
+            "    const body = JSON.parse(response.body);",
+            "    tests['Has results array'] = Array.isArray(body.results);",
+            "    tests('All operations processed', body.results.length > 0);",
+            "} else {",
+            "    tests['Bulk add failed'] = false;",
+            "}"
+          ]
+        }
+      }
+    ]
+  },
+  "req": {
+    "url": "{{baseUrl}}/api/collections/bulk-add-books",
+    "method": "POST",
+    "headers": {
+      "Content-Type": "application/json",
+      "Authorization": "Bearer {{authToken}}"
+    },
+    "body": {
+      "operations": [
+        {
+          "collection_id": "{{collectionId1}}",
+          "book_ids": [
+            "{{bookId1}}",
+            "{{bookId2}}"
+          ]
+        },
+        {
+          "collection_id": "{{collectionId2}}",
+          "book_ids": [
+            "{{bookId3}}"
+          ]
+        }
+      ]
+    }
+  }
+}