Add calendar cache layer, incremental sync tests, completion assertions

- Google Calendar events now cached via CacheFetcher pattern with
  stale-cache fallback on API errors (new migration 015, store methods,
  fetchCalendarEvents handler, BuildTimeline reads from store)
- Todoist incremental sync path covered by 5 new tests
- Task completion tests assert response body, headers, and template data

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

1 files changed, 11 insertions, 0 deletions

diff --git a/migrations/015_calendar_events.sql b/migrations/015_calendar_events.sql
new file mode 100644
index 0000000..071f735
--- /dev/null
+++ b/migrations/015_calendar_events.sql
@@ -0,0 +1,11 @@
+CREATE TABLE IF NOT EXISTS calendar_events (
+    id TEXT PRIMARY KEY,
+    summary TEXT NOT NULL,
+    description TEXT,
+    start_time DATETIME NOT NULL,
+    end_time DATETIME NOT NULL,
+    html_link TEXT,
+    updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+);
+
+CREATE INDEX IF NOT EXISTS idx_calendar_events_start ON calendar_events(start_time);