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.

.dockerignore

@@ -0,0 +1,23 @@
+# Without this, `COPY . .` in the builder stage overwrites the alpine-built node_modules with
+# the host's glibc one — better-sqlite3's compiled addon would then fail to load in the musl
+# runtime image. It also keeps files that should never ship out of the image.
+node_modules
+.next
+.git
+.idea
+
+# Local database, generated config and secrets: the real database arrives via a volume.
+/data
+.env
+.env.local
+.env*.local
+*.db
+*.db-wal
+*.db-shm
+
+# Prisma's generated TypeScript client is reproducible from prisma/schema.prisma.
+/lib/generated
+
+Dockerfile
+docker-compose.yml
+README.md