Refactored the application structure to better separate concerns between files and packages

internal/adapters/inbound/httpapi/query_normalize.go

@@ -0,0 +1,23 @@
+// query_normalize.go normalizes common query values before binding.
+// Layer: adapters/inbound/httpapi request pre-processing.
+package httpapi
+
+import (
+	"net/http"
+	"strings"
+)
+
+func normalizeCommonQueryValue(r *http.Request, key string) {
+	q := r.URL.Query()
+	values, ok := q[key]
+	if !ok || len(values) == 0 {
+		return
+	}
+
+	normalized := strings.ToLower(strings.TrimSpace(values[0]))
+	if normalized == values[0] {
+		return
+	}
+	q.Set(key, normalized)
+	r.URL.RawQuery = q.Encode()
+}