feat: add application date to members

tests/test_repository.py

@@ -25,6 +25,7 @@ def test_repository_creates_transparent_member_record(tmp_path) -> None:
         nickname="Enchantress",
         email="ada@example.org",
         birth_date="1990-12-10",
+        application_date="30.07.2026",
         member_number="0042",
     )
 
@@ -38,6 +39,7 @@ def test_repository_creates_transparent_member_record(tmp_path) -> None:
     raw = json.loads((member_dir / "member.json").read_text(encoding="utf-8"))
     assert raw["person"]["first_name"] == "Ada"
     assert raw["person"]["nickname"] == "Enchantress"
+    assert raw["membership"]["application_date"] == "2026-07-30"
     assert raw["schema_version"] == 1
     assert raw["membership"]["ended_at"] == ""
     assert raw["content_hash"]
@@ -121,6 +123,18 @@ def test_repository_accepts_local_date_input_and_rejects_invalid_dates(tmp_path)
         repository.create_member(first_name="Invalid", last_name="Date", birth_date="31.02.2000")
 
 
+def test_existing_member_without_application_date_stays_empty(tmp_path) -> None:
+    repository = MemberRepository(tmp_path)
+    repository.initialize()
+    member = repository.create_member(first_name="Legacy", last_name="Member")
+    path = repository.members_root / member.member_id / "member.json"
+    raw = json.loads(path.read_text(encoding="utf-8"))
+    raw["membership"].pop("application_date")
+    path.write_text(json.dumps(raw), encoding="utf-8")
+
+    assert repository.get_member(member.member_id).application_date == ""
+
+
 def test_repository_reports_empty_contributions_file(tmp_path) -> None:
     repository = MemberRepository(tmp_path)
     repository.initialize()