fix: skip already applied migrations

cmd/migrate/main.go

@@ -25,7 +25,20 @@ func main() {
 		os.Exit(1)
 	}
 	defer pool.Close()
-	for _, path := range []string{"migrations/000001_mvp.sql", "migrations/000002_growth_analyst.sql", "migrations/000003_ai_summary_refresh.sql", "migrations/000004_ai_page_insights.sql"} {
+	migrations := []struct {
+		version int64
+		path    string
+	}{{1, "migrations/000001_mvp.sql"}, {2, "migrations/000002_growth_analyst.sql"}, {3, "migrations/000003_ai_summary_refresh.sql"}, {4, "migrations/000004_ai_page_insights.sql"}}
+	for _, item := range migrations {
+		var applied bool
+		if err := pool.QueryRow(ctx, `SELECT EXISTS(SELECT 1 FROM schema_migrations WHERE version=$1)`, item.version).Scan(&applied); err != nil {
+			logger.Error("checking migration version failed", "version", item.version, "error", err)
+			os.Exit(1)
+		}
+		if applied {
+			continue
+		}
+		path := item.path
 		migration, err := os.ReadFile(path)
 		if err != nil {
 			logger.Error("reading migration failed", "path", path, "error", err)