feat(01-01): define DB schema, configure Drizzle Kit, write seed script

- Created src/lib/db/schema.ts with users table (id, email, password_hash, created_at)
- Created src/lib/db/index.ts exporting db singleton via Drizzle + Neon HTTP driver
- Created drizzle.config.ts pointing to schema.ts with postgresql dialect
- Created scripts/seed.ts reading AGENT_EMAIL/AGENT_PASSWORD to create hashed user row
- Generated drizzle/0000_milky_black_cat.sql migration (committed per user decision)
- db:migrate and db:seed pending user Neon database setup

teressa-copeland-homes/drizzle/meta/_journal.json

@@ -0,0 +1,13 @@
+{
+  "version": "7",
+  "dialect": "postgresql",
+  "entries": [
+    {
+      "idx": 0,
+      "version": "7",
+      "when": 1773948629637,
+      "tag": "0000_milky_black_cat",
+      "breakpoints": true
+    }
+  ]
+}