feat(shots): previous/next shot navigation on the shot page

Prev/next buttons beside the breadcrumb walk the project's shot list in
the same order as the Shots tab. The ordering now lives in
lib/shot-order.ts, shared by the project page and the shot API.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/api/shots/[shotId]/route.ts

@@ -1,6 +1,7 @@
 import { NextRequest, NextResponse } from "next/server";
 import { auth } from "@/auth";
 import { db } from "@/lib/db";
+import { sortShotsForList } from "@/lib/shot-order";
 
 export async function GET(
   req: NextRequest,
@@ -38,9 +39,35 @@ export async function GET(
 
   const project = await db.project.findUnique({
     where: { id: shot.projectId },
-    select: { name: true },
+    select: {
+      name: true,
+      projectType: true,
+      shots: {
+        orderBy: { createdAt: "asc" },
+        select: {
+          id: true,
+          shotCode: true,
+          episode: true,
+          scene: true,
+          shotNumber: true,
+          shotGroup: { select: { name: true } },
+        },
+      },
+    },
   });
 
+  // Neighbours in the project page's shot list order, for prev/next navigation
+  const orderedShots = project ? sortShotsForList(project.shots, project.projectType) : [];
+  const shotIndex = orderedShots.findIndex((s) => s.id === shotId);
+  const neighbour = (i: number) =>
+    shotIndex >= 0 && orderedShots[i] ? { id: orderedShots[i].id, shotCode: orderedShots[i].shotCode } : null;
+  const shotNav = {
+    prev: neighbour(shotIndex - 1),
+    next: neighbour(shotIndex + 1),
+    position: shotIndex + 1,
+    total: orderedShots.length,
+  };
+
   const [tasks, artists] = await Promise.all([
     db.task.findMany({
       where: { shotId },
@@ -99,6 +126,7 @@ export async function GET(
   return NextResponse.json({
     shot: shotSerialized,
     projectName: project?.name ?? "",
+    shotNav,
     canApprove,
     canInternallyApprove: ["ADMIN", "PRODUCER", "SUPERVISOR"].includes(session.user.role as string),
     tasks,