Add feature toggles system with settings UI (#74)

- Add feature_toggles table (migration 012)
- Add source_config table for future source selection (migration 013)
- Create settings page at /settings with:
  - Feature toggle management (enable/disable/create/delete)
  - Data source configuration (sync and toggle boards/calendars)
- Add store methods for feature toggles and source config
- Add GetCalendarList and GetTaskLists to Google API clients
- Document feature toggle workflow in DESIGN.md

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/internal/api/google_calendar.go b/internal/api/google_calendar.go
index d2d4355..68d423b 100644
--- a/internal/api/google_calendar.go
+++ b/internal/api/google_calendar.go
@@ -175,3 +175,24 @@ func (c *GoogleCalendarClient) GetEventsByDateRange(ctx context.Context, start,
 
 	return deduplicateEvents(allEvents), nil
 }
+
+// GetCalendarList returns all calendars accessible to the user
+func (c *GoogleCalendarClient) GetCalendarList(ctx context.Context) ([]models.CalendarInfo, error) {
+	list, err := c.srv.CalendarList.List().Do()
+	if err != nil {
+		return nil, fmt.Errorf("failed to fetch calendar list: %w", err)
+	}
+
+	var calendars []models.CalendarInfo
+	for _, item := range list.Items {
+		name := item.Summary
+		if name == "" {
+			name = item.Id
+		}
+		calendars = append(calendars, models.CalendarInfo{
+			ID:   item.Id,
+			Name: name,
+		})
+	}
+	return calendars, nil
+}