macOS port groundwork — core, server, tools, and tests now build and run on
macOS 26.5 / Apple Silicon. ctest --preset dev green 21/21 (2 consecutive runs).
apple-dev produces valid arm64 libvoicecat.a + XCFramework for the Swift Package.
Three real cross-platform bugs found and fixed (all latent on Windows/Linux):
1. test_m2_voice.cpp POSIX branch missing <netdb.h> — Linux glibc transitively
includes it, macOS doesn't. Would fail on any strict POSIX system.
2. SIGPIPE killing processes on macOS — writing to a closed TCP socket raises
SIGPIPE by default (doesn't exist on Windows, benign on Linux). Fixed by
ignoring SIGPIPE in both core client init and server startup (POSIX-only,
#ifndef _WIN32). Production fix, not just tests.
3. Use-after-free of Asio's kqueue reactor on server shutdown — the
deterministic test_tofu_flow segfault. TcpServerConn's tls_read_loop runs on
a blocking-I/O thread; when Server::run() returned, io_context was destroyed
while those threads were still running. On macOS kqueue the reactor pointer
is null'd immediately -> segfault in socket.close(). Latent on Windows IOCP
and Linux epoll. Fix: TcpAcceptor now tracks connections; new shutdown()
closes all + joins threads before io is destroyed; Server::stop() now closes
acceptor + media_relay too (was just io.stop()).
Verified: dev + apple-dev presets build green, 21/21 tests pass, server starts
+ two vccli text chat over TLS (M1 on Mac), vccli --voice starts MIC stream via
CoreAudio (M2 protocol-level), vccli --list-devices enumerates CoreAudio
devices, xcodebuild -create-xcframework produces valid VoiceCatCore.xcframework.
No ABI or proto changes. Docs updated: building.md, clients/apple/README.md,
PROGRESS.md, CLAUDE.md status line.