[Sunrisepeak]

mcpp keeps no operating-system layer of its own (mcpp design 2026-10-26 §25). The capabilities its `modules/platform` carried and this library did not are added here:

• process: `exec` replaces the image on Linux and macOS; elsewhere it starts the program, waits for it and ends with its status. `stdio::output` puts both outputs on one pipe, in the order written.
• fs:
  • `append` writes in one piece; `sync` makes a file or directory durable.
  • `extended` and `windows_extended` give the long-path spelling.
  • `measure` and `measure_now` measure what a volume actually does (NFSv3 among them); `volume_type` names the volume.
  • `place` publishes without replacing, whatever the volume supports; `exchange` swaps two entries.
  • `owner_of` and `writable` answer ownership and write access.
• machine: `processors` (logical, physical, heterogeneous) and `memory_available`.
• stdio: `read_input_for` is a bounded read of input. `output_to_error` sends standard output to standard error for a scope, while the document still reaches the original output.
• terminal: `raw_options::keep_interrupt`.
• windows: `code_page`, `console_output_code_page`, `long_paths_enabled`, `machine_registry_path`, `writable_fixed_drive`. Windows code declares what it calls in `win32.h` and loads advapi32 at run time.

Each new capability has a test in tests/process_test, tests/fs_test and tests/platform_test. They pass natively and as ok images on Linux.