refactor(db): switch records layer to Prisma

- Replace hand-written node:sqlite queries with a Prisma client using
  the better-sqlite3 driver adapter
- Version the schema with migrations: baseline table, timestamp
  normalisation, and WAL journal mode
- Store timestamps with an explicit UTC offset so they stop being parsed
  as local time
- Show created/updated times on the edit page, formatted with dayjs
- Move the root redirect into next.config to avoid a prerender error
- Run migrations from the container entrypoint before starting the server

BREAKING CHANGE: DNSMASQ_ADMIN_DB_PATH is replaced by DATABASE_URL, which
must be a Prisma connection URL (file:./data/dnsmasq-admin.db). Existing
database files are migrated in place and need no conversion.

prisma.config.ts

@@ -0,0 +1,15 @@
+// Prisma 7 moved the connection URL out of schema.prisma into this file, and no longer
+// auto-loads .env — hence the explicit dotenv import below. See prisma/schema.prisma for the
+// datamodel and prisma/migrations/ for the SQL actually applied to the database.
+import "dotenv/config"
+import { defineConfig } from "prisma/config"
+
+export default defineConfig({
+  schema: "prisma/schema.prisma",
+  migrations: {
+    path: "prisma/migrations",
+  },
+  datasource: {
+    url: process.env["DATABASE_URL"],
+  },
+})