feat: Log Insights panel — plain English activity summary + safe log disposal

- New route /api/v1/log-insights: analyzes audit logs + security events
  - Shows top IPs with request counts, failures, and top actions
  - Plain English insights (heavy users, auth failures, security alerts)
  - Summary stats: total requests, unique IPs, failed actions
  - Storage info showing log file sizes and entry counts
- New route POST /api/v1/log-insights/dispose: preview-then-confirm cleanup
  - First call shows what would be deleted (preview mode)
  - Second call with confirm:true actually deletes
  - Configurable retention period (default 30 days)
- Frontend panel with modal UI showing insights as cards
  - Period selector (1h, 6h, 24h, 7d)
  - Top visitors table with IP, requests, failures, actions, last seen
  - Storage info footer
  - Clean Old Logs button with preview confirmation dialog
- Wired into app.js and dashboard navbar (🔍 Insights button)
- Addresses QA issue: users need to see who is accessing before cleanup

dashcaddy-api/src/app.js

@@ -93,6 +93,7 @@ const eventsRoutes = require('../routes/events');
 const workflowsRoutes = require('../routes/workflows');
 const dependenciesRoutes = require('../routes/dependencies');
 const securityRoutes = require('../routes/security');
+const logInsightsRoutes = require('../routes/log-insights');
 const billingRoutes = require('../routes/billing');
 const DependencyManager = require('./managers/dependency-manager');
 const autoRestartRoutes = require('../routes/auto-restart');
@@ -753,6 +754,20 @@ async function createApp() {
   apiRouter.use('/security', securityRoutes({
     log: ctx.log,
   }));
+
+  // Log Insights — plain English activity summary + safe log disposal
+  apiRouter.use(logInsightsRoutes({
+    asyncHandler: ctx.asyncHandler,
+    ok: ctx.ok,
+    auditLogger: ctx.auditLogger,
+    securityEventStore: (function() {
+      try {
+        var getStore = require('./security/event-store').getStore;
+        return getStore();
+      } catch (e) { return null; }
+    })()
+  }));
+
   apiRouter.use('/dependencies', dependenciesRoutes({
     dependencyManager: ctx.dependencyManager,
     servicesStateManager: ctx.servicesStateManager,