test(http): 防止集成测试误用非测试数据库

原因：共享迁移辅助函数会直接对 AI_GATEWAY_TEST_DATABASE_URL 指向的数据库执行迁移，需要在任何写入前阻止误连非测试库。

影响：HTTP 集成测试仅允许名称明确包含 test 边界的数据库；不影响未配置数据库环境变量时的普通单元测试。

风险：自定义测试库名称若不符合规则会被拒绝，需要改用 test、test_*、*_test 或包含 _test_ 的名称。

验证：gofmt 无差异；env -u AI_GATEWAY_TEST_DATABASE_URL go test ./... -count=1 通过。

apps/api/internal/httpapi/core_flow_integration_test.go

@@ -2009,6 +2009,7 @@ func applyMigration(t *testing.T, ctx context.Context, databaseURL string) {
 		t.Fatalf("connect migration db: %v", err)
 	}
 	defer pool.Close()
+	requireDedicatedIntegrationTestDatabase(t, ctx, pool)
 	if _, err := pool.Exec(ctx, `
 CREATE TABLE IF NOT EXISTS schema_migrations (
   version text PRIMARY KEY,

apps/api/internal/httpapi/integration_database_safety_test.go

@@ -0,0 +1,54 @@
+package httpapi
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+func requireDedicatedIntegrationTestDatabase(t *testing.T, ctx context.Context, pool *pgxpool.Pool) {
+	t.Helper()
+	var databaseName string
+	if err := pool.QueryRow(ctx, `SELECT current_database()`).Scan(&databaseName); err != nil {
+		t.Fatalf("read integration test database name: %v", err)
+	}
+	if !isDedicatedIntegrationTestDatabase(databaseName) {
+		t.Fatalf(
+			"AI_GATEWAY_TEST_DATABASE_URL must reference a dedicated test database; refusing to use %q",
+			databaseName,
+		)
+	}
+}
+
+func isDedicatedIntegrationTestDatabase(databaseName string) bool {
+	normalized := strings.ToLower(strings.TrimSpace(databaseName))
+	return normalized == "test" ||
+		strings.HasPrefix(normalized, "test_") ||
+		strings.HasSuffix(normalized, "_test") ||
+		strings.Contains(normalized, "_test_")
+}
+
+func TestDedicatedIntegrationTestDatabaseName(t *testing.T) {
+	t.Parallel()
+	for _, testCase := range []struct {
+		name     string
+		database string
+		allowed  bool
+	}{
+		{name: "documented local test database", database: "easyai_ai_gateway_test_codex", allowed: true},
+		{name: "test prefix", database: "test_gateway", allowed: true},
+		{name: "test suffix", database: "gateway_test", allowed: true},
+		{name: "production database", database: "easyai_ai_gateway", allowed: false},
+		{name: "similar production name", database: "gateway_contest", allowed: false},
+	} {
+		testCase := testCase
+		t.Run(testCase.name, func(t *testing.T) {
+			t.Parallel()
+			if got := isDedicatedIntegrationTestDatabase(testCase.database); got != testCase.allowed {
+				t.Fatalf("isDedicatedIntegrationTestDatabase(%q) = %v, want %v", testCase.database, got, testCase.allowed)
+			}
+		})
+	}
+}