fix(tests): the recurrence stand-ins come from fake_note, not a bare MagicMock (#3164)

Four tests predating the helper built their note with MagicMock(), which is
truthy on every attribute nobody set. update_note now reads verify_with, so
the stand-in claimed to carry a check and the milestone-317 guard refused the
write.

That is note 2109 exactly, and the reason fake_note exists: a stand-in has to
be able to say NO. The product behaviour is right — a real column is None or a
string, so this cannot happen outside a test.

Observation, not changed here: fake_note sets is_task=False but leaves
`status` unset, so it too is a truthy mock on the column is_task is derived
FROM. Nothing depends on it today; worth making self-consistent when something
does.

tests/test_recurrence.py

@@ -1,13 +1,23 @@
-"""Tests for task lifecycle timestamps and recurrence logic."""
+"""Tests for task lifecycle timestamps and recurrence logic.
+
+The note stand-ins come from `fake_note`, not a bare MagicMock. These four
+predated that helper and broke the moment `update_note` started reading a
+column they did not set (milestone 317): a fresh MagicMock is truthy on every
+attribute, so `verify_with` read as "this record carries a check" and the
+guard refused the write. That is note 2109's lesson, and the reason fake_note
+exists — a stand-in has to be able to say NO.
+"""
 from datetime import date, datetime, timezone
 from unittest.mock import AsyncMock, MagicMock, patch
 
+from tests.helpers import fake_note, make_mock_session
+
 
 # ── Timestamp side-effect tests ──────────────────────────────────────────────
 
 async def test_update_note_sets_started_at_on_in_progress():
     """started_at is set when status transitions to in_progress."""
-    mock_note = MagicMock()
+    mock_note = fake_note()
     mock_note.status = "in_progress"
     mock_note.started_at = None
     mock_note.recurrence_rule = None
@@ -28,7 +38,7 @@ async def test_update_note_sets_started_at_on_in_progress():
 
 async def test_update_note_sets_completed_at_on_done():
     """completed_at is set when status transitions to done."""
-    mock_note = MagicMock()
+    mock_note = fake_note()
     mock_note.status = "done"
     mock_note.started_at = datetime(2026, 3, 1, tzinfo=timezone.utc)
     mock_note.completed_at = None
@@ -50,7 +60,7 @@ async def test_update_note_sets_completed_at_on_done():
 
 async def test_update_note_clears_timestamps_on_todo():
     """started_at and completed_at are cleared when status resets to todo."""
-    mock_note = MagicMock()
+    mock_note = fake_note()
     mock_note.status = "todo"
     mock_note.started_at = datetime(2026, 3, 1, tzinfo=timezone.utc)
     mock_note.completed_at = datetime(2026, 3, 15, tzinfo=timezone.utc)
@@ -74,7 +84,7 @@ async def test_update_note_clears_timestamps_on_todo():
 async def test_update_note_preserves_started_at_if_already_set():
     """started_at is not overwritten on a second transition to in_progress."""
     original_start = datetime(2026, 3, 1, tzinfo=timezone.utc)
-    mock_note = MagicMock()
+    mock_note = fake_note()
     mock_note.status = "in_progress"
     mock_note.started_at = original_start
     mock_note.recurrence_rule = None
@@ -96,7 +106,6 @@ async def test_update_note_preserves_started_at_if_already_set():
 # ── Recurrence rule validation ────────────────────────────────────────────────
 
 import pytest
-from tests.helpers import make_mock_session
 
 
 def test_validate_interval_rule_valid():