feat: add 7 new features — exec shell, SSE events, compose import, docker resources, resource limits, email notifications, auto-updates

- Container exec/shell via WebSocket + xterm.js (subtle >_ button on cards)
- Live dashboard updates via SSE (resource alerts, health changes, update notices)
- Docker Compose import with YAML parsing, preview, and dependency-ordered deploy
- Volume & network management modal with disk usage overview
- CPU/memory resource limits on deploy and live update
- Email SMTP notifications (nodemailer) alongside Discord/Telegram/ntfy
- Scheduled auto-update scheduler with maintenance windows (daily/weekly/monthly)

New deps: ws, js-yaml, nodemailer

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

status/js/app-selector.js

@@ -181,6 +181,22 @@
               </div>
               <div id="volume-mounts-list" style="display: grid; gap: 8px;"></div>
             </div>
+            <div style="margin-top: 12px;">
+              <label class="form-label-accent-sm">⚙️ Resource Limits</label>
+              <div style="font-size: 0.8rem; color: var(--muted); margin-bottom: 8px;">
+                Optional CPU and memory constraints. Leave at 0 for unlimited.
+              </div>
+              <div style="display: grid; grid-template-columns: 1fr 1fr; gap: 10px;">
+                <div>
+                  <label for="deploy-cpu-limit" style="display: block; font-size: 0.78rem; color: var(--muted); margin-bottom: 4px;">CPU Cores</label>
+                  <input type="number" id="deploy-cpu-limit" value="0" min="0" max="64" step="0.25" class="form-input-card" style="width: 100%;" placeholder="0 = unlimited" />
+                </div>
+                <div>
+                  <label for="deploy-memory-limit" style="display: block; font-size: 0.78rem; color: var(--muted); margin-bottom: 4px;">Memory (MB)</label>
+                  <input type="number" id="deploy-memory-limit" value="0" min="0" max="131072" step="64" class="form-input-card" style="width: 100%;" placeholder="0 = unlimited" />
+                </div>
+              </div>
+            </div>
           </div>
         </details>
       </div>
@@ -920,7 +936,11 @@
       tailscaleOnly: document.getElementById('deploy-tailscale-only').checked,
       mediaPath: mediaPath || null,
       plexClaimToken: document.getElementById('deploy-plex-claim')?.value.trim() || null,
-      customVolumes: customVolumes.length > 0 ? customVolumes : null
+      customVolumes: customVolumes.length > 0 ? customVolumes : null,
+      resources: {
+        cpus: parseFloat(document.getElementById('deploy-cpu-limit').value) || 0,
+        memory: parseFloat(document.getElementById('deploy-memory-limit').value) || 0,
+      }
     };
 
     // Validate subdomain