Skip PTY resizes for pixel-only changes and coalesce pending resize
events.
Snap standalone terminal layout to whole device pixels to avoid subpixel
jitter.

before:


https://github.com/user-attachments/assets/0ad0db83-0099-44c8-b8d1-3dc8146b25ef


after:


https://github.com/user-attachments/assets/86278014-1c87-4263-a9e5-b58bcc1fa2ea




Release Notes:

- Fixed: Reduce terminal flicker on resize

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Signed-off-by: pigletfly <wangbing.adam@gmail.com>
Co-authored-by: Ben Kunkle <ben@zed.dev>