Mino chapter-08

Added

• Chapter 08 project file tools: read_file, write_file, and edit_file, confined
  to the startup project directory with os.Root. Symbolic-link targets, special
  files, multiple hard links, non-UTF-8 text, and files over 64 KiB are refused.
• read_file is a confined read and needs no approval. write_file requires an
  explicit create or overwrite mode; edit_file replaces one exact fragment that
  occurs once. Each write or edit shows a bounded preview and requires separate
  default-deny approval bound to the inspected file content; a file changed after
  approval is not written. Writes publish atomically through a synced temporary file.
• File tools are unavailable when the project directory contains ~/.mino, such as
  when Mino starts in the home directory, so unapproved reads cannot expose settings
  or session history.

Changed

• Tools may implement a live-only inspection step before approval; history replay
  still validates recorded arguments without reading project files. History records
  remain version 4, but chapter-07 cannot load sessions that started file tools.
• Extend the default SOUL with file tool guidance, preserving existing user SOUL files.