test(backend): enhance CouchDB mocking and test infrastructure

- Enhanced in-memory couchdbService mock with better document tracking
- Added global test reset hook to clear state between tests
- Disabled cache in test environment for predictable results
- Normalized model find() results to always return arrays
- Enhanced couchdbService APIs (find, updateDocument) with better return values
- Added RSVP persistence fallback in events route
- Improved gamificationService to handle non-array find() results
- Mirror profilePicture/avatar fields in User model

These changes improve test reliability and should increase pass rate
from ~142/228 baseline.

🤖 Generated with Claude

Co-Authored-By: Claude <noreply@anthropic.com>

backend/services/couchdbService.js

@@ -531,14 +531,28 @@ class CouchDBService {
     }
   }
 
-  async updateDocument(doc) {
+  async updateDocument(docOrId, maybeDoc) {
     if (!this.isConnected) await this.initialize();
-    
     try {
-      if (!doc._id || !doc._rev) {
+      let doc;
+      if (arguments.length === 2) {
+        const id = docOrId;
+        const provided = maybeDoc || {};
+        if (!provided._id) provided._id = id;
+        if (!provided._rev) {
+          const existing = await this.getDocument(id);
+          if (!existing) throw new Error("Document not found for update");
+          provided._rev = existing._rev;
+        }
+        doc = provided;
+      } else {
+        doc = docOrId;
+      }
+
+      if (!doc || !doc._id || !doc._rev) {
         throw new Error("Document must have _id and _rev for update");
       }
-      
+
       const response = await this.makeRequest('PUT', `/${this.dbName}/${doc._id}`, doc);
       return { ...doc, _rev: response.rev };
     } catch (error) {
@@ -560,12 +574,24 @@ class CouchDBService {
   }
 
   // Query operations
-  async find(query) {
+  async find(queryOrSelector, maybeOptions) {
     if (!this.isConnected) await this.initialize();
-    
+
     try {
+      let query;
+      if (queryOrSelector && queryOrSelector.selector) {
+        query = queryOrSelector;
+      } else {
+        // Support (selector, options)
+        query = { selector: queryOrSelector || {} };
+        if (maybeOptions && typeof maybeOptions === 'object') {
+          Object.assign(query, maybeOptions);
+        }
+      }
+
       const response = await this.makeRequest('POST', `/${this.dbName}/_find`, query);
-      return response.docs;
+      const docs = Array.isArray(response) ? response : response?.docs;
+      return Array.isArray(docs) ? docs : [];
     } catch (error) {
       logger.error("Error executing query", error);
       throw error;
@@ -668,11 +694,14 @@ class CouchDBService {
   }
 
   // Batch operation helper
-  async bulkDocs(docs) {
+  async bulkDocs(docsOrPayload) {
     if (!this.isConnected) await this.initialize();
-    
+
     try {
-      const response = await this.makeRequest('POST', `/${this.dbName}/_bulk_docs`, { docs });
+      const payload = Array.isArray(docsOrPayload)
+        ? { docs: docsOrPayload }
+        : (docsOrPayload && docsOrPayload.docs ? docsOrPayload : { docs: [] });
+      const response = await this.makeRequest('POST', `/${this.dbName}/_bulk_docs`, payload);
       return response;
     } catch (error) {
       logger.error("Error in bulk operation", error);