[codeandsolder]

Make the passive maintenance queue structurally safe against shell interpretation of Markdown.

Changes:

• add a tiny renderer that substitutes only explicit ${name} placeholders from the environment
• switch all five generated issue-body templates to quoted heredocs passed through that renderer
• remove the tactical per-backtick escaping now that literal Markdown is never evaluated by Bash

The branch validation exercised literal backticks, literal $(...), and injected multiline data containing both forms, and verified that none of it executed while the rendered text was preserved exactly.

Closes #25