feat: catch-all page for stopped apps, deploy controls, dashboard open button

Stopped/undeployed app subdomains now show a branded page instead of
Traefik 404. Deploy settings page gains start/stop/restart controls.
Dashboard shows "Megnyitás" button for running apps.

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

controller/internal/web/templates/deploy.html

@@ -6,7 +6,20 @@
         <a href="/stacks" class="btn btn-sm btn-outline">← Vissza</a>
         <h2>{{.Meta.DisplayName}} — {{if .AlreadyDeployed}}Beállítások{{else}}Telepítés{{end}}</h2>
     </div>
-    <a href="/apps/{{.Meta.Slug}}" class="btn btn-sm btn-outline">ℹ️ Részletek</a>
+    <div style="display:flex;align-items:center;gap:.5rem">
+        {{if .AlreadyDeployed}}
+            {{if isOperational .Stack.State}}
+                <button class="btn btn-sm btn-warning" onclick="stackAction(event, '{{.Stack.Name}}', 'restart')">Újraindítás</button>
+                <button class="btn btn-sm btn-danger" onclick="stackAction(event, '{{.Stack.Name}}', 'stop')">Leállítás</button>
+            {{else}}
+                <button class="btn btn-sm btn-success" onclick="stackAction(event, '{{.Stack.Name}}', 'start')">Indítás</button>
+            {{end}}
+            {{if and (isOperational .Stack.State) .EffectiveSubdomain}}
+                <a href="https://{{.EffectiveSubdomain}}.{{.Domain}}" target="_blank" class="btn btn-sm btn-outline">Megnyitás ↗</a>
+            {{end}}
+        {{end}}
+        <a href="/apps/{{.Meta.Slug}}" class="btn btn-sm btn-outline">ℹ️ Részletek</a>
+    </div>
 </div>
 
 <div class="deploy-container">