fix: remove uuid-ossp extension dependency for CI compatibility

The embedded PostgreSQL in CI lacks libossp-uuid shared library.
Since UUID v7 is generated at the application layer (Rust uuid crate),
uuid-ossp is unnecessary. Use pgcrypto's gen_random_uuid() for tests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: yoyo930021

migrations/0001_init.sql

@@ -1,3 +1,4 @@
 -- Enable required PostgreSQL extensions
-CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
+-- Note: uuid-ossp is NOT used; UUID v7 is generated at the application layer
+-- pgcrypto provides gen_random_uuid() and cryptographic functions
 CREATE EXTENSION IF NOT EXISTS "pgcrypto";

tests/db_test.rs

@@ -15,13 +15,13 @@ async fn test_database_connection_and_migration() {
 }
 
 #[tokio::test]
-async fn test_uuid_extension_available() {
+async fn test_pgcrypto_extension_available() {
     let ctx = TestContext::new().await;
 
-    let row: (uuid::Uuid,) = sqlx::query_as("SELECT uuid_generate_v4()")
+    let row: (uuid::Uuid,) = sqlx::query_as("SELECT gen_random_uuid()")
         .fetch_one(&ctx.pool)
         .await
-        .expect("uuid-ossp extension should be available");
+        .expect("pgcrypto extension should be available");
 
     assert_eq!(row.0.get_version_num(), 4);
 }