Fix 7 frontend security vulnerabilities (4 critical, 3 high)

- Escape all innerHTML assignments with user/external data across 12 JS files
- Upgrade credential encryption: per-value IV, key moved to sessionStorage
- Fix open redirect in TOTP auth via proper URL hostname validation
- Remove sensitive DNS topology data from localStorage cache
- Add security regression test suite (51 tests)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

status/js/error-logs.js

@@ -39,7 +39,7 @@
         content.innerHTML = '<div style="padding: 20px; color: var(--bad-fg);">❌ Failed to load error logs</div>';
       }
     } catch (error) {
-      content.innerHTML = `<div style="padding: 20px; color: var(--bad-fg);">❌ Error loading logs: ${error.message}</div>`;
+      content.innerHTML = `<div style="padding: 20px; color: var(--bad-fg);">❌ Error loading logs: ${escapeHtml(error.message)}</div>`;
     }
   }