Interprocess pipe support (for stdout/stderr capture) (#866)

- **RAII pipe handles for child process stdout/stderr capture**: `StdoutPipeHandles` is now a proper RAII type with automatic cleanup, move semantics, and partial close support. This makes it safe to use pipes for capturing child process output without risking handle/fd leaks.

- **Optional separate stderr pipe**: `CreateProcOptions` now accepts a `StderrPipe` field so callers can capture stdout and stderr independently. When null (default), stderr shares the stdout pipe as before.

- **LogStreamListener with pluggable handler**: The TCP log stream listener accepts connections from remote processes and delivers parsed log lines through a `LogStreamHandler` interface, set dynamically via `SetHandler()`. This allows any client to receive log messages without depending on a specific console implementation.

- **TcpLogStreamSink for zen::logging**: A logging sink that forwards log messages to a `LogStreamListener` over TCP, using the native `zen::logging::Sink` infrastructure with proper thread-safe synchronization.

- **Reliable child process exit codes on Linux**: `waitpid` result handling is fixed so `ProcessHandle::GetExitCode()` returns the real exit code. `ProcessHandle::Reset()` reaps zombies directly, replacing the global `IgnoreChildSignals()` which prevented exit code collection entirely. Also fixes a TOCTOU race in `ProcessHandle::Wait()` on Linux/Mac.

- **Pipe capture test suite**: Tests covering stdout/stderr capture via pipes (both shared and separate modes), RAII cleanup, move semantics, and exit code propagation using `zentest-appstub` as the child process.

- **Service command integration tests**: Shell-based integration tests for `zen service` covering the full lifecycle (install, status, start, stop, uninstall) on all three platforms — Linux (systemd), macOS (launchd), and Windows (SCM via PowerShell).

- **Test script reorganization**: Platform-specific test scripts moved from `scripts/test_scripts/` into `scripts/test_linux/`, `test_mac/`, and `test_windows/`.

1 files changed, 43 insertions, 0 deletions

diff --git a/scripts/test_mac/block-clone-test.sh b/scripts/test_mac/block-clone-test.sh
new file mode 100755
index 000000000..1a9575dcf
--- /dev/null
+++ b/scripts/test_mac/block-clone-test.sh
@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+# Test block-clone functionality on macOS (APFS).
+#
+# APFS is the default filesystem on modern Macs and natively supports
+# clonefile(), so no special setup is needed — just run the tests.
+#
+# Usage:
+#   ./scripts/test_mac/block-clone-test.sh [path-to-zencore-test]
+#
+# If no path is given, defaults to build/macosx/<arch>/debug/zencore-test
+# relative to the repository root.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+ARCH="$(uname -m)"
+TEST_BINARY="${1:-$REPO_ROOT/build/macosx/$ARCH/debug/zencore-test}"
+
+if [ ! -x "$TEST_BINARY" ]; then
+    echo "error: test binary not found or not executable: $TEST_BINARY" >&2
+    echo "hint:  build with 'xmake config -m debug && xmake build zencore-test'" >&2
+    exit 1
+fi
+
+# Verify we're on APFS
+BINARY_DIR="$(dirname "$TEST_BINARY")"
+FS_TYPE="$(diskutil info "$(df "$BINARY_DIR" | tail -1 | awk '{print $1}')" 2>/dev/null | grep "Type (Bundle)" | awk '{print $NF}' || true)"
+
+if [ "$FS_TYPE" != "apfs" ]; then
+    echo "warning: filesystem does not appear to be APFS (got: ${FS_TYPE:-unknown}), clone tests may skip" >&2
+fi
+
+TEST_CASES="TryCloneFile,CopyFile.Clone,SupportsBlockRefCounting,CloneQueryInterface"
+
+echo "Running block-clone tests ..."
+echo "---"
+"$TEST_BINARY" \
+    --test-suite="core.filesystem" \
+    --test-case="$TEST_CASES"
+echo "---"
+echo "All block-clone tests passed."