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, 2 insertions, 0 deletions

diff --git a/src/zenutil/config/loggingconfig.cpp b/src/zenutil/config/loggingconfig.cpp
index 5092c60aa..e2db31160 100644
--- a/src/zenutil/config/loggingconfig.cpp
+++ b/src/zenutil/config/loggingconfig.cpp
@@ -29,6 +29,8 @@ ZenLoggingCmdLineOptions::AddCliOptions(cxxopts::Options& options, ZenLoggingCon
 		("log-critical", 	"Change selected loggers to level CRITICAL", 				cxxopts::value<std::string>(LoggingConfig.Loggers[logging::Critical]))
 		("log-off", 		"Change selected loggers to level OFF", 					cxxopts::value<std::string>(LoggingConfig.Loggers[logging::Off]))
 		("otlp-endpoint", 	"OpenTelemetry endpoint URI (e.g http://localhost:4318)", 	cxxopts::value<std::string>(LoggingConfig.OtelEndpointUri))
+		("force-color",		"Force colored log output even when stdout is not a terminal",	cxxopts::value<bool>(LoggingConfig.ForceColor)->default_value("false"))
+		("log-stream",		"TCP log stream endpoint (host:port)",							cxxopts::value<std::string>(LoggingConfig.LogStreamEndpoint))
 	;
 	// clang-format on
 }