feat(persons): add notes field to person profile (issue #23)

V5 Flyway migration adds TEXT notes column; Person entity, service, and
controller updated to persist notes. Frontend edit form adds textarea and
view mode renders the notes section. Backed by 2 new service unit tests
(persist + blank clears).

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

frontend/messages/de.json

@@ -111,6 +111,8 @@
 	"person_btn_merge": "Zusammenführen",
 	"person_btn_merge_confirm": "Ja, zusammenführen",
 	"person_merge_warning": "Achtung: Diese Aktion ist nicht rückgängig zu machen.",
+	"person_label_notes": "Notizen",
+	"person_placeholder_notes": "Biographische Hinweise, Besonderheiten…",
 	"person_docs_heading": "Gesendete Dokumente",
 	"person_no_docs": "Diese Person ist noch nicht als Absender verknüpft.",
 

frontend/messages/en.json

@@ -111,6 +111,8 @@
 	"person_btn_merge": "Merge",
 	"person_btn_merge_confirm": "Yes, merge",
 	"person_merge_warning": "Warning: This action cannot be undone.",
+	"person_label_notes": "Notes",
+	"person_placeholder_notes": "Biographical notes, remarks…",
 	"person_docs_heading": "Sent documents",
 	"person_no_docs": "This person has not yet been linked as a sender.",
 

frontend/messages/es.json

@@ -111,6 +111,8 @@
 	"person_btn_merge": "Fusionar",
 	"person_btn_merge_confirm": "Sí, fusionar",
 	"person_merge_warning": "Atención: Esta acción no se puede deshacer.",
+	"person_label_notes": "Notas",
+	"person_placeholder_notes": "Notas biográficas, observaciones…",
 	"person_docs_heading": "Documentos enviados",
 	"person_no_docs": "Esta persona aún no está vinculada como remitente.",