fix(server): keep Claude probe closures inside the bounded cache

Carry the probe in the cache key instead of a side map that was never
pruned, so evicted entries release their probe and captured environment.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CeWArRh6FDJGzjGYecyi7A
c5ff1c8b39Claude committed on 9/25/2026, 11:39:09 PMparent705037c
1 file changedLine totals unavailable