improvement: some improvement done for appointment and treatment shared components.

frontend/messages/en.json

@@ -573,6 +573,7 @@
     "subtitle": "Search a patient, pick a date, then click a time slot under a provider to book.",
     "loadingSchedule": "Loading schedule…",
     "infoPastViewOnly": "Past appointments are view-only.",
+    "infoEditBlockedHasTreatment": "This appointment cannot be edited because a treatment is linked to it.",
     "infoSelectPatient": "Select a patient before booking.",
     "errorOutsideHours": "This appointment falls outside the provider's current working hours and cannot be edited.",
     "successUpdated": "Appointment updated.",