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/core/logs.js

@@ -138,7 +138,7 @@
         logsContent.innerHTML = `
           <div style="padding: 20px; text-align: center; color: var(--bad-fg);">
             <div style="font-size: 1.2rem; margin-bottom: 8px;">⚠️ Error</div>
-            <div>${result.error}</div>
+            <div>${escapeHtml(result.error)}</div>
           </div>`;
         return;
       }
@@ -167,7 +167,7 @@
     } catch (error) {
       logsContent.innerHTML = `
         <div style="padding: 20px; text-align: center; color: var(--bad-fg);">
-          Failed to fetch logs: ${error.message}
+          Failed to fetch logs: ${escapeHtml(error.message)}
         </div>`;
     }
   }
@@ -400,7 +400,7 @@
         logsContent.innerHTML = `
           <div style="padding: 20px; text-align: center; color: var(--bad-fg);">
             <div style="font-size: 1.2rem; margin-bottom: 8px;">⚠️ Error</div>
-            <div>${result.error}</div>
+            <div>${escapeHtml(result.error)}</div>
           </div>`;
         return;
       }
@@ -429,7 +429,7 @@
     } catch (error) {
       logsContent.innerHTML = `
         <div style="padding: 20px; text-align: center; color: var(--bad-fg);">
-          Failed to fetch logs: ${error.message}
+          Failed to fetch logs: ${escapeHtml(error.message)}
         </div>`;
     }
   }
@@ -544,7 +544,7 @@
         logsContent.innerHTML = `
           <div style="padding: 20px; text-align: center; color: var(--bad-fg);">
             <div style="font-size: 1.2rem; margin-bottom: 8px;">⚠️ Error</div>
-            <div>${result.error}</div>
+            <div>${escapeHtml(result.error)}</div>
           </div>`;
         return;
       }
@@ -569,7 +569,7 @@
     } catch (error) {
       logsContent.innerHTML = `
         <div style="padding: 20px; text-align: center; color: var(--bad-fg);">
-          Failed to fetch logs: ${error.message}
+          Failed to fetch logs: ${escapeHtml(error.message)}
         </div>`;
     }
   }