fix: bigint serialization 500s in video and approval responses

Two endpoints return 500 whenever they succeed, because their success
payloads include VideoVersion rows whose sizeBytes column is a BigInt
that JSON.stringify rejects:

- PATCH /api/projects/[projectId]/videos/[videoId] included all versions;
  respond with scalar video fields only, which is all any caller reads
- POST /api/approvals/[requestId]/decision included the full version row
  in the resolved request; select the scalar fields the response and
  notifications actually use

The approval bug is reachable the first time any approver responds to a
request; the decision itself commits, but the requester sees an error.

Co-Authored-By: Claude Fable 5 <[email protected]>

app/api/approvals/[requestId]/decision/route.ts

@@ -157,10 +157,17 @@ export async function POST(request: NextRequest, { params }: RouteParams) {
                 approver: { select: { id: true, name: true, email: true, image: true } },
               },
             },
+            // Scalar fields only: the full version row carries BigInt sizeBytes,
+            // which JSON.stringify rejects when serializing the response.
             version: {
-              include: {
+              select: {
+                id: true,
+                versionNumber: true,
+                versionLabel: true,
                 video: {
-                  include: {
+                  select: {
+                    id: true,
+                    title: true,
                     project: { select: { id: true, name: true } },
                   },
                 },