Add configuration files and update project documentation

- Introduced .editorconfig for consistent coding styles across the project.
- Added .golangci.yml for Go linting configuration.
- Updated AGENTS.md to clarify project structure and components.
- Enhanced CONTRIBUTING.md with Makefile usage for common tasks.
- Updated Dockerfiles to use Go 1.24 and improved build instructions.
- Refined README.md and deployment documentation for clarity.
- Added testing documentation in testing.md for backend and frontend tests.
- Introduced Makefile for streamlined development commands and tasks.

internal/app/services/client_test.go

@@ -0,0 +1,32 @@
+package services_test
+
+import (
+	"testing"
+
+	"github.com/andyleap/hnh-map/internal/app/services"
+)
+
+func TestFixMultipartContentType_NeedsQuoting(t *testing.T) {
+	ct := "multipart/form-data; boundary=----WebKitFormBoundary=abc123"
+	got := services.FixMultipartContentType(ct)
+	want := `multipart/form-data; boundary="----WebKitFormBoundary=abc123"`
+	if got != want {
+		t.Fatalf("expected %q, got %q", want, got)
+	}
+}
+
+func TestFixMultipartContentType_AlreadyQuoted(t *testing.T) {
+	ct := `multipart/form-data; boundary="----WebKitFormBoundary"`
+	got := services.FixMultipartContentType(ct)
+	if got != ct {
+		t.Fatalf("expected unchanged, got %q", got)
+	}
+}
+
+func TestFixMultipartContentType_Normal(t *testing.T) {
+	ct := "multipart/form-data; boundary=----WebKitFormBoundary"
+	got := services.FixMultipartContentType(ct)
+	if got != ct {
+		t.Fatalf("expected unchanged, got %q", got)
+	}
+}