fix(events): Update NocoDB query syntax to match official API documentation

- Use btw (between) operator for date ranges instead of gte/lte
- Use proper ~or and ~and logical operators for complex conditions
- Use like operator with %wildcards% for search functionality
- Role-based filtering with correct OR conditions for board visibility
- All query syntax now matches official NocoDB v2 API documentation

This should resolve the 422 Unprocessable Entity errors by using the
correct query parameter format that NocoDB expects.

server/utils/nocodb-events.ts

@@ -62,13 +62,49 @@ export function createNocoDBEventsClient() {
       if (filters?.limit) queryParams.set('limit', filters.limit.toString());
       if (filters?.offset) queryParams.set('offset', filters.offset.toString());
       
-      // Build where clause for filtering using simple NocoDB v2 syntax
-      // Start with just the status filter to test basic functionality
+      // Build where clause for filtering using correct NocoDB v2 syntax
+      const whereConditions: string[] = [];
+      
+      if (filters?.start_date && filters?.end_date) {
+        // Date range filtering using btw (between) operator
+        whereConditions.push(`(start_datetime,btw,${filters.start_date},${filters.end_date})`);
+      }
+      
+      if (filters?.event_type) {
+        whereConditions.push(`(event_type,eq,${filters.event_type})`);
+      }
+      
+      if (filters?.visibility) {
+        whereConditions.push(`(visibility,eq,${filters.visibility})`);
+      } else if (filters?.user_role) {
+        // Role-based visibility filtering
+        if (filters.user_role === 'user') {
+          whereConditions.push(`(visibility,eq,public)`);
+        } else if (filters.user_role === 'board') {
+          // Board members can see public and board-only events
+          whereConditions.push(`~or((visibility,eq,public),(visibility,eq,board-only))`);
+        }
+        // Admin sees all events (no filter)
+      }
+      
       if (filters?.status) {
-        queryParams.set('where', `(status,eq,${filters.status})`);
+        whereConditions.push(`(status,eq,${filters.status})`);
       } else {
-        // Default to active events only - test this simple query first
-        queryParams.set('where', `(status,eq,active)`);
+        // Default to active events only
+        whereConditions.push(`(status,eq,active)`);
+      }
+      
+      if (filters?.search) {
+        // Search in title or description using like operator
+        whereConditions.push(`~or((title,like,%${filters.search}%),(description,like,%${filters.search}%))`);
+      }
+      
+      // Combine conditions with ~and if multiple conditions exist
+      if (whereConditions.length > 0) {
+        const whereClause = whereConditions.length === 1 
+          ? whereConditions[0] 
+          : `~and(${whereConditions.join(',')})`;
+        queryParams.set('where', whereClause);
       }
       
       // Sort by start date