feat(trips): trip tracking with analytics, tag conversion, and transaction assignment

Adds trips table usage across API and UI: trip CRUD, per-trip analytics
(category/daily/merchant/tag/participant breakdowns), tag-to-trip
conversion, trip assignment via transaction overrides, and trip filter
in the transactions view. Recovered from working tree after local git
corruption; feature was already live via host-context Docker builds.

src/app/api/transactions/bulk/route.ts

@@ -1,5 +1,6 @@
 import { NextRequest, NextResponse } from "next/server";
 import { prisma, queryRaw } from "@/lib/db";
+import { assignTransactionsToTrip } from "@/lib/queries";
 
 export async function POST(req: NextRequest) {
   const body = await req.json();
@@ -77,5 +78,11 @@ export async function POST(req: NextRequest) {
     return NextResponse.json({ updated: ids.length });
   }
 
+  if (action === "assign_trip") {
+    const { trip_id } = body as { ids: number[]; trip_id: number | null };
+    await assignTransactionsToTrip(trip_id, ids);
+    return NextResponse.json({ updated: ids.length });
+  }
+
   return NextResponse.json({ error: "Invalid action" }, { status: 400 });
 }