Rewind now evicts cached file/memory reads for the discarded messages

Rewinding a conversation (rewind_conversation) now evicts cached file and memory reads tied to the discarded messages instead of just dropping them. Claude Code walks the spliced-off messages, determines which files and which nested CLAUDE.md/memory files were read during that span, and clears them from the in-memory read-file cache and from the agent's read-file state via a new evictNestedMemoryPaths callback. Previously a later re-read after a rewind could have served stale cached content for files that changed between the original read and the rewind point.