REFACTORED - Replace Prisma with Drizzle ORM

- Add lib/db (schema, postgres.js client, enums, seed, migrations) on Drizzle
- Rewrite all lib and admin action queries from Prisma to Drizzle
- Keep existing table/column names so no data migration is needed
- Preserve signed-cookie admin auth unchanged
- Map unique-violation handling from Prisma P2002 to SQLSTATE 23505
- Swap deps, scripts, Makefile, and Dockerfile from Prisma to Drizzle

lib/db/migrations/meta/_journal.json

@@ -0,0 +1,13 @@
+{
+  "version": "7",
+  "dialect": "postgresql",
+  "entries": [
+    {
+      "idx": 0,
+      "version": "7",
+      "when": 1786146995564,
+      "tag": "0000_absurd_rawhide_kid",
+      "breakpoints": true
+    }
+  ]
+}