deps: pin to landed upstream releases; retire upstream-fixes note
the three upstream fixes weir surfaced have landed in their proper
homes, so weir now depends on blessed sources instead of the temporary
reference branches:
- zat -> v0.3.7 (release; carries the MST encoding-cache fix + the
collectBlocksInto/corruption fix)
- http.zig -> master (websocket v0.1.7 alignment, merged)
- redis -> main tip 507f69f (retire-read-buffers fix, merged)
removes NOTE-upstream-fixes-needed.md per its own exit condition.
verified: clean build, 6/6 tests, demo flow runs end to end, boot
hydration replays the repo (51 records) without BadBlockHash.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>