Implement dashboard and audit log templates, add paginated audit log support

- Added `web/templates/{dashboard,audit,base,accounts,account_detail}.html` for a consistent UI.
- Implemented new audit log endpoint (`GET /v1/audit`) with filtering and pagination via `ListAuditEventsPaged`.
- Extended `AuditQueryParams`, added `AuditEventView` for joined actor/target usernames.
- Updated configuration (`goimports` preference), linting rules, and E2E tests.
- No logic changes to existing APIs.

web/templates/dashboard.html

@@ -0,0 +1,36 @@
+{{define "dashboard"}}{{template "base" .}}{{end}}
+{{define "title"}}Dashboard — MCIAS{{end}}
+{{define "content"}}
+<div class="page-header">
+  <h1>Dashboard</h1>
+</div>
+<div style="display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:1rem;margin-bottom:1.5rem">
+  <div class="card" style="text-align:center">
+    <div style="font-size:2rem;font-weight:700;color:#2563eb">{{.TotalAccounts}}</div>
+    <div class="text-muted text-small">Total Accounts</div>
+  </div>
+  <div class="card" style="text-align:center">
+    <div style="font-size:2rem;font-weight:700;color:#16a34a">{{.ActiveAccounts}}</div>
+    <div class="text-muted text-small">Active Accounts</div>
+  </div>
+</div>
+{{if .RecentEvents}}
+<div class="card">
+  <h2 style="font-size:1rem;font-weight:600;margin-bottom:1rem">Recent Audit Events</h2>
+  <div class="table-wrapper">
+    <table>
+      <thead><tr><th>Time</th><th>Event</th><th>Actor</th></tr></thead>
+      <tbody>
+        {{range .RecentEvents}}
+        <tr>
+          <td class="text-small text-muted">{{formatTime .EventTime}}</td>
+          <td><code style="font-size:.8rem">{{.EventType}}</code></td>
+          <td class="text-small text-muted">{{.ActorUsername}}</td>
+        </tr>
+        {{end}}
+      </tbody>
+    </table>
+  </div>
+</div>
+{{end}}
+{{end}}