XY-912 Auto-compact safe terminal protocol events

[yvette-carlisle]

Summary

• include safe terminal protocol-event compaction in serve auto-safe runtime maintenance
• preserve active issue, retained worktree, review handoff/orchestration, needs-attention, and terminal-failure ledger-owned runs
• record auto-safe compaction warnings without blocking scheduler polling
• document the 14-day automatic protocol-event retention behavior

Validation

• cargo make fmt
• cargo test -p decodex prune_compacts_only_terminal_unowned_protocol_events --all-features -- --test-threads=1
• cargo test -p decodex auto_safe_prune --all-features -- --test-threads=1
• cargo make lint-fix
• cargo make test
• git diff --check