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/lib/categories.ts

@@ -0,0 +1,33 @@
+export const CATEGORIES = [
+  "groceries",
+  "dining",
+  "transport",
+  "fuel",
+  "shopping",
+  "utilities",
+  "entertainment",
+  "travel",
+  "health",
+  "insurance",
+  "subscriptions",
+  "cash_advance",
+  "government",
+  "education",
+  "rent",
+  "transfers",
+  "income",
+  "personal_care",
+  "pets",
+  "gifts",
+  "charity",
+  "other",
+] as const;
+
+export type Category = (typeof CATEGORIES)[number];
+
+export function formatCategory(cat: string): string {
+  return cat
+    .split("_")
+    .map((w) => w.charAt(0).toUpperCase() + w.slice(1))
+    .join(" ");
+}