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/0000_snapshot.json

@@ -0,0 +1,65 @@
+{
+  "id": "67889008-a13f-4b7e-9a7e-87d0e0ca3fd4",
+  "prevId": "00000000-0000-0000-0000-000000000000",
+  "version": "7",
+  "dialect": "postgresql",
+  "tables": {
+    "public.users": {
+      "name": "users",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true
+        },
+        "email": {
+          "name": "email",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "password_hash": {
+          "name": "password_hash",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "timestamp",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {
+        "users_email_unique": {
+          "name": "users_email_unique",
+          "nullsNotDistinct": false,
+          "columns": [
+            "email"
+          ]
+        }
+      },
+      "policies": {},
+      "checkConstraints": {},
+      "isRLSEnabled": false
+    }
+  },
+  "enums": {},
+  "schemas": {},
+  "sequences": {},
+  "roles": {},
+  "policies": {},
+  "views": {},
+  "_meta": {
+    "columns": {},
+    "schemas": {},
+    "tables": {}
+  }
+}