refactor: use static HIS database per instance

internal/databaseconfig/static_test.go

@@ -0,0 +1,17 @@
+package databaseconfig
+
+import (
+	"context"
+	"errors"
+	"testing"
+)
+
+func TestStaticResolverValidatesCodeWithoutSelectingDatabase(t *testing.T) {
+	resolver := &StaticResolver{code: "RS_BEKASI"}
+	if _, err := resolver.Resolve(context.Background(), " rs_bekasi "); err != nil {
+		t.Fatalf("matching code returned error: %v", err)
+	}
+	if _, err := resolver.Resolve(context.Background(), "RS_JAKARTA"); !errors.Is(err, ErrRSCodeMismatch) {
+		t.Fatalf("wrong code error = %v, want ErrRSCodeMismatch", err)
+	}
+}