feat(pi-session-deck): add setStatus mirror to capture footer statuses into chip files

[robhowley]

• add setStatus wrapper to capture footer-status text into chip files without owning the footer
• wrap ctx.ui.setStatus during session_start to mirror each status call asynchronously
• strip ANSI/control characters, dedupe identical writes, clear on undefined or empty text
• restore as a slim module that only wraps setStatus — no footer replacement
• update README and chips/index.ts exports
• add 13 mirror tests covering install, write, clear, dedupe, and edge cases