feat(render): always-available, fully-cancel render controls

The backend cancel was solid (CancelJob/StopJob; the dev worker abandons a cancelled
job, a real node kills its process) — but the UI couldn't reach it: the render page
had NO cancel button, and the global progress pill's X only HID the pill (the job kept
running). So a render couldn't actually be stopped from where you watch it.

- Render page: a prominent «لغو رندر» button while a render is in flight (Queued or
  Running); cancelRender() calls /renders/:id/cancel and returns to config optimistically.
  The poll now also handles a `cancelled` status (when stopped from another surface).
- Global pill: the X now CANCELS the render (with confirm) instead of just hiding it —
  so any in-flight render is cancellable from any page.
- (Dashboard MyRenders already had a working cancel.)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/[locale]/studio/render/[projectId]/page.tsx

@@ -10,6 +10,7 @@ import {
   Link2,
   Loader2,
   RefreshCw,
+  XCircle,
 } from "lucide-react";
 
 import { useLocale } from "next-intl";
@@ -205,6 +206,12 @@ export default function RenderPage() {
         } else if (data.status === "failed") {
           setPhase("failed");
           setErrorMessage(data.errorMessage ?? "Render failed.");
+        } else if (data.status?.toLowerCase() === "cancelled") {
+          // Cancelled here or from another surface (pill / dashboard) — reflect it.
+          setPhase("config");
+          setProgress(0);
+          setEtaSec(null);
+          setErrorMessage("رندر لغو شد.");
         }
       } catch {
         setPhase("failed");
@@ -279,6 +286,26 @@ export default function RenderPage() {
     }
   }, [projectId, resolution, fps, locale]);
 
+  /** Fully cancel the active render — works in any state (Queued or Running). The
+   *  server marks it Cancelled (the dev worker abandons it, a real node kills its
+   *  process), so it stops fully. Optimistically return to config right away. */
+  const cancelRender = useCallback(async () => {
+    if (!jobId) return;
+    const id = jobId;
+    setPhase("config");
+    setProgress(0);
+    setEtaSec(null);
+    setProgressMessage("");
+    setPreviewB64(null);
+    setErrorMessage("رندر لغو شد.");
+    setJobId(null);
+    try {
+      await apiFetch(`/api/renders/${id}/cancel`, { method: "POST" });
+    } catch {
+      /* server is the source of truth; the dashboard can also cancel */
+    }
+  }, [jobId]);
+
   const backToStudio = `/studio/video/${projectId}`;
   const isBusy = phase === "submitting" || phase === "polling";
 
@@ -393,9 +420,19 @@ export default function RenderPage() {
             </button>
           </div>
         ) : isBusy ? (
-          <p className="text-sm text-gray-400">
+          <div className="flex w-full max-w-md flex-col items-center gap-3">
+            <p className="text-center text-sm text-gray-400">
               می‌توانید این صفحه را ببندید؛ رندر در پس‌زمینه ادامه می‌یابد و از هر صفحه‌ای قابل پیگیری است.
             </p>
+            <button
+              type="button"
+              onClick={cancelRender}
+              className="inline-flex items-center justify-center gap-2 rounded-lg border border-red-900/60 bg-red-950/40 px-5 py-2.5 text-sm font-medium text-red-300 transition-colors hover:bg-red-900/40"
+            >
+              <XCircle className="h-4 w-4" />
+              لغو رندر
+            </button>
+          </div>
         ) : (
           // Config
           <div className="w-full max-w-md space-y-5">

src/components/render/GlobalRenderProgress.tsx

@@ -103,16 +103,25 @@ export function GlobalRenderProgress({ authed }: { authed: boolean }) {
         </div>
       </div>
 
-      {/* Dismiss (hides until job id changes) */}
+      {/* Cancel — fully stops the render server-side (works from any page). */}
       <span
         role="button"
         tabIndex={-1}
-        onClick={(e) => {
+        onClick={async (e) => {
           e.stopPropagation();
-          setDismissed(active.id);
+          if (!window.confirm("این رندر لغو شود؟")) return;
+          const id = active.id;
+          setActive(null);
+          setDismissed(id);
+          try {
+            await fetch(`/api/renders/${id}/cancel`, { method: "POST" });
+          } catch {
+            /* server is the source of truth; ignore transient errors */
+          }
         }}
-        className="shrink-0 rounded p-1 text-gray-600 hover:text-gray-300"
+        className="shrink-0 rounded p-1 text-gray-500 transition-colors hover:bg-red-500/20 hover:text-red-300"
-        aria-label="پنهان کردن"
+        aria-label="لغو رندر"
+        title="لغو رندر"
       >
         <X className="h-3.5 w-3.5" />
       </span>