Replace KJ_DEFER with kj::defer#210

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Sjors wants to merge 3 commits intobitcoin-core:masterfrom

Sjors:2025/08/kj-defer

Commits on Sep 2, 2025

doc: describe ThreadContext struct and synchronization requirements
ryanofsky
committed
bug: fix ProxyClient<Thread> deadlock if disconnected as IPC call is returning
ryanofsky
committed

Commits on Sep 10, 2025

Replace KJ_DEFER with kj::defer
Sjors
committed