feat(finals): prominent finalist-docs banner on jury dashboard + gate nav to finals jury

Grand-Final jurors couldn't find the finalist documents review: the only entry
point was a top-nav text link (hidden in the hamburger on mobile), with nothing
on the dashboard. Add a prominent dashboard banner (shown only to finals-jury
members) linking to /jury/finals-documents, and gate the nav "Finalist Documents"
link to members so other jurors don't hit a dead "No access" page.

- finalist.canReviewDocuments: lightweight boolean procedure (self-resolves active
  program) so the nav can gate the link without fetching the full payload
- jury-nav: show "Finalist Documents" only when canReviewDocuments
- jury dashboard: FinalsJuryBanner server component, gated via userCanReviewFinals,
  rendered above content regardless of assignment state

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/server/routers/finalist.ts

@@ -1683,6 +1683,17 @@ export const finalistRouter = router({
     }),
 
   /** Read-only review of all finalists' grand-final documents (admins + finale jury). */
+  /** Lightweight boolean — may the current user open the finalist documents review? Self-resolves the active program so the nav can gate the link without fetching the full payload. */
+  canReviewDocuments: protectedProcedure.query(async ({ ctx }) => {
+    const program = await ctx.prisma.program.findFirst({
+      where: { status: 'ACTIVE' },
+      orderBy: { year: 'desc' },
+      select: { id: true },
+    })
+    if (!program) return false
+    return userCanReviewFinals(ctx.prisma, ctx.user.id, ctx.user.role, program.id)
+  }),
+
   listReviewDocuments: protectedProcedure
     .input(z.object({ programId: z.string() }))
     .query(async ({ ctx, input }) => {