Follow-ups on top of @DonutsDelivery's salvaged reaper commit (#64141):
- create_from_config() now parses lsp.idle_timeout (invalid values fall
back to DEFAULT_IDLE_TIMEOUT) — previously the constructor knob was
unreachable from config.yaml (config exposure adapted from #36892 by
@0xbWy and #68091 by @9miya20)
- canonical default declared in hermes_cli DEFAULT_CONFIG so config
discovery surfaces the knob (per sweeper review note on #64980)
- reaper loop survives transient sweep errors instead of dying and
silently re-opening the leak (gap flagged in #68091 review)
- eventlog.log_reaped(): one INFO line per sweep + clears the
log_active announce cache so respawns re-announce at INFO
- docs: replace the stale 'no idle-timeout reaper' paragraph with the
new lifecycle description + config reference
- tests: reuse-refresh protection (the regression teknium's sweeper
requested on #64141), reaper-survives-error, config propagation,
invalid-value fallback, DEFAULT_CONFIG/manager-constant sync