Prevent shell history expansion from corrupting Issue Monster safe-output comments

[Copilot]

Issue Monster comments were intermittently posted with injected command-wrapper text (for example ___BEGIN___COMMAND_OUTPUT_MARKER___) instead of the intended message. Root cause was shell history expansion on !* inside Copilot!** when safeoutputs CLI calls were executed through a shell.

• Root cause containment at execution boundary

  • Disabled shell history expansion for safeoutputs command execution (set +H / set +o histexpand) so comment bodies are passed verbatim.
  • Ensures shell metacharacter sequences in markdown do not mutate tool arguments.

• Template hardening

  • Updated the Issue Monster comment template to avoid the !* pattern in bold markdown text.
  • Preserves rendered output while removing the expansion trigger.

• Behavioral impact

  • add_comment payloads now remain byte-stable from agent output through MCP tool call to final GitHub comment.
  • Eliminates marker leakage into user-visible issue comments.

# before invoking safeoutputs commands
set +o histexpand  # equivalent: set +H

safeoutputs add_comment --item_number "$ISSUE" --body "$COMMENT_BODY"