Add timeline events for all WhatsApp contact timestamps

Extract ZABOUTEXPIRATIONTIMESTAMP and emit a timeline event for each
timestamp stored on a WhatsApp contact record: disappearing messages
timer changes, "about" text changes and scheduled expiry, and contact
record updates. ContactsV2.sqlite stores no other date attributes in
any released schema version.

tests/ios_backup/test_whatsapp_contacts.py

@@ -25,6 +25,8 @@ class TestWhatsappContactsModule:
         assert alice["disappearing_mode_is_on"] is True
         assert alice["disappearing_mode_label"] == "24 hours"
         assert alice["disappearing_mode_timestamp"] == "2025-07-23 21:46:40.000000"
+        assert alice["about_timestamp"] == "2025-07-12 08:00:00.000000"
+        assert alice["about_expiration_timestamp"] == "2025-08-16 01:20:00.000000"
         assert alice["last_updated"] == "2025-08-04 11:33:20.000000"
 
         bob = next(r for r in m.results if r["given_name"] == "Bob")
@@ -34,11 +36,43 @@ class TestWhatsappContactsModule:
         assert bob["disappearing_mode_label"] == "off"
         assert bob["disappearing_mode_timestamp"] is None
 
-        assert len(m.timeline) == 1
-        assert m.timeline[0]["event"] == "disappearing_mode_set"
-        assert m.timeline[0]["timestamp"] == "2025-07-23 21:46:40.000000"
-        assert "24 hours" in m.timeline[0]["data"]
-        assert "14155550100@s.whatsapp.net" in m.timeline[0]["data"]
+        # Alice: disappearing_mode_set, about_changed, about_expiration and
+        # contact_last_updated. Bob: contact_last_updated only.
+        assert len(m.timeline) == 5
+
+        events = {
+            (entry["event"], entry["timestamp"]): entry["data"]
+            for entry in m.timeline
+        }
+        assert (
+            "24 hours"
+            in events[("disappearing_mode_set", "2025-07-23 21:46:40.000000")]
+        )
+        assert (
+            "14155550100@s.whatsapp.net (Alice Example)"
+            in events[("disappearing_mode_set", "2025-07-23 21:46:40.000000")]
+        )
+        assert (
+            'changed to "Hey there! I am using WhatsApp."'
+            in events[("about_changed", "2025-07-12 08:00:00.000000")]
+        )
+        assert (
+            "scheduled to expire"
+            in events[("about_expiration", "2025-08-16 01:20:00.000000")]
+        )
+
+        updated = [
+            entry["data"]
+            for entry in m.timeline
+            if entry["event"] == "contact_last_updated"
+        ]
+        assert len(updated) == 2
+        assert all(
+            entry["timestamp"] == "2025-08-04 11:33:20.000000"
+            for entry in m.timeline
+            if entry["event"] == "contact_last_updated"
+        )
+        assert any("14155550101@s.whatsapp.net (Bob Example)" in d for d in updated)
 
         assert len(m.alertstore.alerts) == 0