ui: Apply everywhere — power toggles, plan preview, no start/stop/install

Rework the dashboard around convergence:
- ServiceControls / ServiceCard / JobCard: replace start/restart/stop
  with a Power toggle (set enabled → apply, i.e. activate/deactivate)
  plus Restart (the one imperative bounce).
- ToolDetail: install/uninstall becomes an Enable/Disable toggle;
  `installed` stays the live state, `enabled` the desired one.
- ConfigPanel Apply and CreateDeploymentForm now POST /apply (one
  converge that renders + restarts only what changed) instead of
  /deploy + a separate start/restart.
- New ConvergePanel on Overview: a terraform-style Preview (POST /apply
  plan=true) showing would-activate/restart/deactivate, then Apply.
- useApply + useSetEnabled hooks; `enabled` added to Service/Job/
  Deployment types; both handle the self-restart connection drop.

Backend: PUT /config/deployments/{name}/enabled sets desired on/off
(edit config; caller runs apply) — the declarative toggle the UI uses.

Dashboard builds clean (tsc + vite); 59 API tests pass; live /apply and
/services?enabled verified after an api restart.

app/src/pages/ServiceDetail.tsx

@@ -51,7 +51,7 @@ export function ServiceDetailPage() {
         {!isStatic && (
           <div className="flex items-center gap-2">
             {health && <HealthBadge status={health.status} latency={health.latency_ms} />}
-            <ServiceControls name={deployment.id} health={health} />
+            <ServiceControls name={deployment.id} enabled={deployment.enabled} />
           </div>
         )}
       </DetailHeader>