#1957)

Small cleanup pass over today's react-router→tanstack and
react-cmdk→native-CommandPalette migrations:

- CommandPalette: drop the now-meaningless "matches react-cmdk's
  filterItems" comment (react-cmdk no longer exists) and fix the
  focus comment that called a callback ref "the effect above".
- DayViewContent: remove the unused `toggleTaskList` useCallback
  (dead since #1935; Biome noUnusedVariables, non-blocking warning).
- Fix the command palette placeholder hint: `'code'` matched no
  command label, so the suggested search returned nothing. Swapped
  for `'feedback'` (matches "Share Feedback") in both day and week.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>