feat(pipeline): skip the preview build and inherit the previous one

Some exports are deliberately framed differently from their review —
unscaled or un-punched-in EXRs — and a preview rebuilt from those frames
would be the wrong picture. The previous export's MOV is the correct one.

skipPreview renders the EXRs and goes straight to READY_FOR_QC. Available
at Queue Export (a "No preview" checkbox in the panel, E1 field) and as an
option when overriding a validation failure.

The inheritance is as important as the skip: deliveryMovPath, the review
MP4, the thumbnail and the Version are carried over from the newest
earlier export of that shot which has them. Without it the delivery
builder — which takes its MOV from deliveryMovPath — would package EXRs
with no MOV at all. Where there is nothing to inherit, the export still
reaches QC and the timeline says it has no review media.

QC is untouched by any of this: a skipped preview still needs a human
pass before the export can be delivered.

Panel 2.3.0. Adds migration 20260814000000_export_skip_preview.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/api/ext/exports/route.ts

@@ -5,7 +5,7 @@ import { createExport } from "@/lib/render-pipeline/exports";
 
 // ── POST /api/ext/exports (E1 — Queue Export) ────────────────────────────────
 //
-// Body: { manifest: RenderManifest, submittedByEmail?, priority?, force? }
+// Body: { manifest: RenderManifest, submittedByEmail?, priority?, force?, skipPreview? }
 // The server decides the new version number, updates Shot.shotVersion/exrOutput,
 // supersedes older non-terminal exports, and creates Export(QUEUED) + RenderJob.
 
@@ -20,6 +20,7 @@ export async function POST(req: NextRequest) {
     force?: boolean;
     vfxScope?: string | null;
     submissionNote?: string | null;
+    skipPreview?: boolean;
   };
   try {
     body = await req.json();
@@ -38,6 +39,7 @@ export async function POST(req: NextRequest) {
       // undefined inherits the shot's previous export values
       vfxScope: body.vfxScope,
       submissionNote: body.submissionNote,
+      skipPreview: body.skipPreview === true,
     });
     return NextResponse.json(result, { status: 201 });
   } catch (err) {