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

agents/event-triage/meta.json

@@ -0,0 +1,20 @@
+{
+  "name": "Event triage",
+  "description": "Hidden background agent. Spawned periodically by the scheduler. Processes pending MCP events (email, WhatsApp, calendar), evaluates relevance, and notifies the user via notify() when something is worth surfacing. Ephemeral: session is discarded as soon as the turn ends.",
+  "friendly_description": "Background agent that periodically reviews incoming email, WhatsApp, and calendar events and pings you when something matters.",
+  "i18n": {
+    "it": {
+      "name": "Triage eventi",
+      "friendly_description": "Agente in background che esamina periodicamente email, WhatsApp ed eventi del calendario e ti avvisa quando qualcosa è importante."
+    },
+    "fr": {
+      "name": "Tri des événements",
+      "friendly_description": "Agent en arrière-plan qui examine périodiquement les e-mails, WhatsApp et les événements du calendrier et vous avertit quand quelque chose compte."
+    }
+  },
+  "type": "system",
+  "inject_skills": false,
+  "inject_memory": ["user-memory/index.md"],
+  "icon": "icon.png",
+  "strength": "low"
+}