zagent 0.0.224

• The TUI paints streaming frames by cell diff: on a same-width frame it
  rewrites only the rows that changed (cursor moves + erase + the row
  payload) instead of repainting the whole live region, and identical
  frames emit zero bytes. Cell-grid model underneath tracks grapheme
  wide-char continuation and canonical SGR slots.
• Kitty keyboard protocol support: the TUI decodes CSI-u key events
  (functional keys, modified keys, caps/num-lock modifier bits masked)
  with exact-match gates per binding.
• A bounded terminal-replay oracle (replayTerminal) models screen,
  scrollback, and DECSTBM scroll margins — region-only scroll, reverse
  index, absolute cursor addressing, and deferred wrap — for sharper
  paint-path tests.
• Rate-limit advice now quotes the provider's wire retry-after value
  ("retry in ~6s (provider retry-after)") instead of claiming the
  provider sent none.