fix: implement comprehensive UI/UX and code organization improvements

CSRF Form Enhancements:
- Add optional onError callback prop for better error handling
- Remove CSRF token from console logging for security
- Provide user-friendly error notifications instead of silent failures

Date Filter Optimization:
- Refactor sessions route to avoid object mutation issues
- Build date filters cleanly without relying on spreading existing objects
- Prevent potential undefined startTime mutations

Geographic Threat Map Optimization:
- Extract country names to reusable constants in lib/constants/countries.ts
- Calculate max values once to avoid repeated expensive operations
- Centralize threat level color mapping to eliminate duplicated logic
- Replace repeated color assignments with centralized THREAT_LEVELS configuration

Accessibility Improvements:
- Add keyboard support to audit log table rows (Enter/Space keys)
- Include proper ARIA labels and focus management
- Add tabIndex for screen reader compatibility
- Enhance focus indicators with ring styling

Performance & Code Organization:
- Move COUNTRY_NAMES to shared constants for reusability
- Optimize calculation patterns in threat mapping components
- Reduce redundant logic and improve maintainability

app/api/dashboard/sessions/route.ts

@@ -41,19 +41,20 @@ function buildWhereClause(
   }
 
   // Date Range Filter
+  const dateFilters: { gte?: Date; lt?: Date } = {};
+
   if (startDate) {
-    whereClause.startTime = {
-      ...((whereClause.startTime as object) || {}),
-      gte: new Date(startDate),
-    };
+    dateFilters.gte = new Date(startDate);
   }
+
   if (endDate) {
     const inclusiveEndDate = new Date(endDate);
     inclusiveEndDate.setDate(inclusiveEndDate.getDate() + 1);
-    whereClause.startTime = {
-      ...((whereClause.startTime as object) || {}),
-      lt: inclusiveEndDate,
-    };
+    dateFilters.lt = inclusiveEndDate;
+  }
+
+  if (Object.keys(dateFilters).length > 0) {
+    whereClause.startTime = dateFilters;
   }
 
   return whereClause;

app/dashboard/audit-logs/page.tsx

@@ -367,8 +367,16 @@ export default function AuditLogsPage() {
                 {auditLogs.map((log) => (
                   <TableRow
                     key={log.id}
-                    className="cursor-pointer hover:bg-gray-50"
+                    className="cursor-pointer hover:bg-gray-50 focus:bg-gray-100 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:ring-inset"
                     onClick={() => setSelectedLog(log)}
+                    onKeyDown={(e) => {
+                      if (e.key === "Enter" || e.key === " ") {
+                        e.preventDefault();
+                        setSelectedLog(log);
+                      }
+                    }}
+                    tabIndex={0}
+                    aria-label={`View details for ${eventTypeLabels[log.eventType] || log.eventType} event`}
                   >
                     <TableCell className="font-mono text-sm">
                       {formatDistanceToNow(new Date(log.timestamp), {