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/src/lib/generated/api.ts

@@ -307,6 +307,7 @@ export interface components {
             firstName: string;
             lastName: string;
             alias?: string;
+            notes?: string;
         };
         DocumentUpdateDTO: {
             title?: string;