## Description:
Cut worker→main bandwidth ~3.3× by switching PlayerUpdate from a full
per-tick snapshot to a field-level diff. PlayerImpl.toUpdate() now
caches the last sent update and returns only changed fields, or null if
nothing changed. The client-side applyStateUpdate() merges instead of
overwriting.
Per-tick total dropped from ~297 KB to ~89 KB; the Player bucket alone
went from 258 KB/tick to 50 KB/tick. Diff/apply logic lives in a new
GameUpdateUtils.ts module with unit tests.
## Please complete the following:
- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
## Please put your Discord username so you can be contacted if a bug or
regression is found:
evan
Evan