A newline in --subject or --from injected arbitrary frontmatter lines
and a premature '---' terminator into the message file (review §4).
Newlines now collapse to spaces and remaining control characters are
dropped; content is preserved on one line. Four regression checks
added first (failed 4/4 against the unfixed script), selftest 44/44.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HBbjgS5A55RVavoyjJC4FX
coord-send.sh, coord-inbox.sh, coord-done.sh and the 40-check
coord-selftest.sh, unchanged, as the extraction baseline. Selftest
passes 40/40 in this location (script paths are dir-relative).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HBbjgS5A55RVavoyjJC4FX
