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

SKALD.md

@@ -129,7 +129,7 @@ All agents now have **Vector Paintings** icons (painterly vector, warm and famil
 
 | Agent | Animal | Status |
 |-------|--------|--------|
-| TIC | 🕷️ Spider | ✅ |
+| Event triage | 🕷️ Spider | ✅ |
 | Private Memory Lint | ✨ Firefly | ✅ |
 | Shared Memory Lint | 🐝 Bee | ✅ |
 ### Refactoring — completed ✅