file_read, file_write, file_edit, file_grep, and file_glob now check
paths against the sandbox config before operating. Same policy that
landrun enforces on execute_code, applied at the application level.
- Add sandbox.LoadMerged: loads base config + named layer, graceful
fallback if layer missing. Replaces duplicated logic in execute.
- Add sandbox.CheckPath: resolves symlinks, expands templates, checks
path against allowed entries (RO/ROX for read, RW/RWX for write).
- file.Server.checkAccess wires the check into every file dispatch.
2d122c70dd