feat: initial finance SPA — phases 1 & 2

Next.js 16 personal finance dashboard connected to postgres-personal.

Phase 1 (Foundation):
- API routes: GET /api/transactions (paginated, filterable, sortable),
  GET /api/statements, GET /api/merchants
- Transactions data table with date/category/bank/search filters, pagination, sort
- Statements card grid with period, due date, amount, transaction count
- Sidebar layout with nav for all planned sections

Phase 2 (Normalisation):
- PATCH /api/transactions/[id] — upsert transaction_overrides
- POST /api/transactions/bulk — bulk categorize/normalize
- Inline click-to-edit category (22 options) and merchant name
- Blue dot override indicator, bulk action bar
- Effective values via COALESCE(override, llm_value) pattern

Stack: Next.js 16 (App Router, standalone), Prisma 7.x + @prisma/adapter-pg,
TanStack Query, Tailwind CSS. Auth via Traefik chain-oauth@file.

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

@@ -0,0 +1,42 @@
+import { NextRequest, NextResponse } from "next/server";
+import { prisma } from "@/lib/db";
+
+export async function POST(req: NextRequest) {
+  const body = await req.json();
+  const { action, ids, category, merchant_normalized } = body as {
+    action: string;
+    ids: number[];
+    category?: string;
+    merchant_normalized?: string;
+  };
+
+  if (!ids || !Array.isArray(ids) || ids.length === 0) {
+    return NextResponse.json({ error: "ids required" }, { status: 400 });
+  }
+
+  if (action === "categorize" && category) {
+    const ops = ids.map((id) =>
+      prisma.transaction_overrides.upsert({
+        where: { transaction_id: id },
+        update: { category_override: category, updated_at: new Date() },
+        create: { transaction_id: id, category_override: category },
+      })
+    );
+    await prisma.$transaction(ops);
+    return NextResponse.json({ updated: ids.length });
+  }
+
+  if (action === "normalize" && merchant_normalized) {
+    const ops = ids.map((id) =>
+      prisma.transaction_overrides.upsert({
+        where: { transaction_id: id },
+        update: { merchant_normalized, updated_at: new Date() },
+        create: { transaction_id: id, merchant_normalized },
+      })
+    );
+    await prisma.$transaction(ops);
+    return NextResponse.json({ updated: ids.length });
+  }
+
+  return NextResponse.json({ error: "Invalid action" }, { status: 400 });
+}