fix(aibox): batch H audit fixes - subagent cancel propagation, scheduler timeout, exec process-group reaping
Fourth audit round (see docs/reports/aibox_audit_20260817.md §11):
- H1: shared parent cancel event no longer cleared on subagent first think
(N5 regression); parent-already-cancelled skips subagent start
- M1: /reload_prompts moved off event loop (run_in_executor, N3 sibling)
- M2: skill --help scan prewarmed before serving connections
- M3: scheduler task-level timeout (scheduler.task_timeout, default 600s)
- M4: get_recent_memories(None) capped instead of full-table load
- M5: memo delete now physically removes rows (was complete-only)
- M6: PromptManager.reload builds new list then atomically swaps
- L1-L12: read_file arg coercion, proxy save failure reported, SSE
utf-8 tolerance, persona realpath check, truncation char boundary,
compressor div0, skill path quoting, ask_user required, POSIX
process-group kill (pgid captured at Popen), web scheme whitelist,
registry redact substring match, Bearer redaction in failover logs
qing
d3acccd146