Fix standard-stream inheritance and platform log chunking

[bkaradzic-microsoft]

Follow-up to #233, addressing Gary's review.

Changes

• Make private saved/reader descriptors non-inheritable: F_DUPFD_CLOEXEC on POSIX and cleared kernel handle inheritance on Windows, while preserving CRT descriptor modes.
• Use pipe2(O_CLOEXEC) on Android. Keep the checked pipe/fcntl fallback on Apple, which has no pipe2.
• Save and restore each target descriptor's inheritance flags during redirection, Stop, and rollback. Preserve Windows standard-handle behavior, including unavailable GUI descriptors (_get_osfhandle returning -2).
• Enforce byte limits before emitting complete lines as well as unterminated output. Retain the 3,800-byte Windows/Android limit; use 1,023-byte Apple default chunks and 255-byte Apple error chunks, reserving the string terminator within the documented persisted-content budgets.
• Preserve UTF-8 boundaries, CRLF, and intentional blank lines. Platform chunking does not alter the tee to the original stream.
• Add regression coverage for lifecycle inheritance, original-byte preservation, complete/partial lines, exact boundaries, UTF-8, and POSIX descriptor flags. Wire the new cases into desktop/Apple and Android unit-test targets.

Process-creation limitation

Apple's pipe/fcntl fallback and Windows' CRT duplication followed by inheritance-flag restoration are not atomic with concurrent child-process creation. The API now explicitly requires applications to serialize child creation with Start()/Stop() to avoid those windows. The Windows implementation deliberately retains _dup/_dup2 to preserve CRT text/binary/Unicode and other descriptor state rather than rebuilding descriptors with incomplete state.

[Copilot]

🟡 Changes recommended

Gate or explicitly enable the pipe2 feature declaration for the desktop POSIX test target.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Updates standard-stream redirection to prevent descriptor inheritance and adds platform-specific diagnostic log chunking with regression coverage.

Changes:

• Preserves descriptor flags while enforcing non-inheritance.
• Adds bounded, UTF-8-aware platform log chunking.
• Expands lifecycle, descriptor, and chunking tests.

File summaries

File	Summary
Tests/UnitTests/Shared/StandardStreamLoggerPosix.cpp	POSIX descriptor tests
Tests/UnitTests/Shared/StandardStreamLoggerLines.cpp	Chunking and UTF-8 tests
Tests/UnitTests/Shared/StandardStreamLogger.cpp	Lifecycle and preservation tests
Tests/UnitTests/CMakeLists.txt	Desktop test registration
Tests/UnitTests/Android/app/src/main/cpp/CMakeLists.txt	Android test registration
Core/Foundation/Source/StandardStreamLoggerLines.h	Bounded line processing
Core/Foundation/Source/StandardStreamLogger_Windows.cpp	Windows inheritance handling
Core/Foundation/Source/StandardStreamLogger_Shared.inl	Shared draining and chunk emission
Core/Foundation/Source/StandardStreamLogger_PosixOps.inl	POSIX descriptor and pipe handling
Core/Foundation/Source/StandardStreamLogger_Apple.cpp	Apple log limits
Core/Foundation/Source/StandardStreamLogger_Android.cpp	Android log limits
Core/Foundation/Include/Babylon/StandardStreamLogger.h	API documentation
Core/Foundation/CMakeLists.txt	Foundation source registration

Review details

• Files reviewed: 13/13 changed files
• Comments generated: 1
• Review effort level: Lite

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