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/merchants/route.ts

@@ -0,0 +1,16 @@
+import { NextRequest, NextResponse } from "next/server";
+import { getMerchantSuggestions, getBankNames } from "@/lib/queries";
+
+export async function GET(req: NextRequest) {
+  const search = req.nextUrl.searchParams.get("search");
+  const type = req.nextUrl.searchParams.get("type");
+
+  if (type === "banks") {
+    const banks = await getBankNames();
+    return NextResponse.json(banks.map((b) => b.bank_name));
+  }
+
+  if (!search) return NextResponse.json([]);
+  const merchants = await getMerchantSuggestions(search);
+  return NextResponse.json(merchants.map((m) => m.merchant));
+}