feat(persons): add birth/death year fields (issue #18)

V5 Flyway migration adds birth_year and death_year INTEGER columns.
Service validates birthYear <= deathYear (400 otherwise). Frontend edit
form adds year number inputs; view mode renders * year / † year. Backed
by 3 backend service tests and 1 E2E test.

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

frontend/src/lib/generated/api.ts

@@ -307,6 +307,8 @@ export interface components {
             firstName: string;
             lastName: string;
             alias?: string;
+            birthYear?: number;
+            deathYear?: number;
         };
         DocumentUpdateDTO: {
             title?: string;