safe-bash: add `dos2unix`/`unix2dos` (line-ending conversion)

[kamilio]

Missing: dos2unix/unix2dos. Line-ending conversion is a common pre-processing step.

Behavior: convert CRLF↔LF in place (VFS) or on stdin→stdout; -n IN OUT, keep-BOM handling consistent with the shell's BOM policy. Trivial streaming transform; bound input.

From the safe-bash command gap analysis (2026-09-08). Sandbox constraints apply: bounded input/CPU/memory, VFS-only paths, cooperative cancellation, no host process/network beyond the existing curl authorizer.

[kamilio]

Delivered directly to main in aed6be8 and ede5985; independently verified remote main at ede5985. Adds bounded VFS/stdin dos2unix/unix2dos, in-place and -n conversion, BOM handling, aggregate defaults and root/scoped leaf exports. Original dos2unix 7.4.0-2 source reviewed; finite native stdout/stderr/status/file-effect comparisons and independent safety/lifecycle checks pass. Unsupported native options and ownership/provider limits are documented rather than claimed as universal parity. Validation: 485 focused cases; full maintained npm test, lint, normal build, types, committed archive, package lint, CLI screenshot inspection; fresh packed validation passes all 22 profiles / 43 commands including four type profiles and four zero-external browser bundles executed under Node. Closing after remote delivery; GitHub release publication is being monitored separately.