test: add unit tests for database and Gitea client

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

internal/gitea/client_test.go

@@ -0,0 +1,20 @@
+package gitea
+
+import "testing"
+
+func TestNewClient(t *testing.T) {
+	client, err := NewClient("https://gitea.com", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if client == nil {
+		t.Error("client is nil")
+	}
+}
+
+func TestNewClientInvalidURL(t *testing.T) {
+	_, err := NewClient("://invalid", "")
+	if err == nil {
+		t.Error("expected error for invalid URL")
+	}
+}