v0.8.58

Summary

• Pool dispatch: atomic try_claim_koi_todo fences concurrent activators (heartbeat, auto-pickup, assign_koi); single-turn-per-Koi serialization.
• Busy status: board-aware idle restore — coordinator and desktop call_koi no longer clobber each other's Koi status.
• web_fetch tool: fetch URL and return plain-text body.
• Tool output: shared truncation helpers (head+tail, error-line preservation) for shell/code_run.
• piscis-ide-tools crate: shared LSP / read_lints for openpiscis and AgentZ hosts.
• File tools: improved encoding detection in file_read; file_write / file_search enhancements.

Test plan

• cargo test -p piscis-kernel --test pool_services — 25 tests pass
• Concurrent dispatch regression tests pass