rename the TIC system agent to event triage

TIC said nothing about what the agent does, and named the wrong thing: the
tick belongs to the scheduler, which is generic and lives outside it. The
agent's only decision is whether an incoming event deserves an interruption
— it sorts, it never acts — so it is now event-triage, matching the
functional naming of the two memory lints.

- agents/tic/ -> agents/event-triage/, module tic/ -> event_triage/,
  TicManager -> EventTriageManager, TicConfig -> EventTriageConfig
- agent id and chat source: "tic" -> "event-triage"
- config keys: tic.* -> event_triage.*, and the config.yml section tic: ->
  event_triage: (greenfield: previously set values fall back to defaults)
- i18n en/it/fr: Event triage / Triage eventi / Tri des evenements; dropped
  the stale "TIC sessions" mention from the debug-pages description
- docs/system-agents.md, docs/index.md, docs/settings.md, CLAUDE.md, SKALD.md

web/components/session-detail.js

@@ -21,7 +21,7 @@ function formatTime(iso) {
 }
 
 function sourceBadgeClass(source) {
-  const map = { tic: 'bg-warning text-dark', cron: 'bg-info text-dark', web: 'bg-primary', telegram: 'bg-success', mobile: 'bg-secondary' };
+  const map = { 'event-triage': 'bg-warning text-dark', cron: 'bg-info text-dark', web: 'bg-primary', telegram: 'bg-success', mobile: 'bg-secondary' };
   return map[source] ?? 'bg-secondary';
 }