feat: harden recap cleaning and skip redundant agent recaps

[jms830]

What

Two small, default-on recap-quality improvements, both inspired by patterns in the minimal Dovyski/pi-recap extension, adapted to this codebase.

1. Harden cleanRecap() (subagent/recap.ts)

Models occasionally wrap the recap line in junk. The existing cleaner strips code fences and takes the first non-empty line; this adds normalization for the common wrappers:

• one leading list/enumeration marker (- , * , 1., 2))
• a Recap: / Title: / Summary: label prefix
• surrounding quotes/backticks
• collapsed internal whitespace

Bare leading digits (e.g. 3 files changed) are preserved — only 1./2)-style enumeration markers are stripped. The 100-char cap is unchanged. Verified with a 14-case table including the digit-preservation edge case.

2. Skip redundant agent recaps (index.ts, agent_end)

agent_end can re-fire, and a turn can end with no new natural-language reply. Re-summarizing identical (or empty) assistant text just burns another model call for the same status line. This adds a per-session guard keyed on the last assistant reply text; the recap call is skipped when the key is empty or unchanged from the last successfully-recapped turn. State is cleared on session_shutdown. Goal derivation is unaffected.

Notes

• Both changes are default-on and behavior-preserving for the normal path.
• index.js is regenerated from index.ts via tsc; the diff therefore also re-syncs a bench-CSV-validation section that had drifted from index.ts on main.
• tsc --noEmit is clean.