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

crates/agent-loop/src/manager.rs

@@ -37,7 +37,7 @@ pub trait LiveInput: Send + Sync {
 /// Per-turn metadata.
 #[derive(Debug, Clone, Default)]
 pub struct TurnMeta {
-    /// Synthetic turn (TIC/notify) — no user echo semantics.
+    /// Synthetic turn (event triage, notify) — no user echo semantics.
     pub synthetic:     bool,
     /// Interactive surface (web chat, telegram, …).
     pub interactive:   bool,

crates/agent-loop/src/store.rs

@@ -143,7 +143,7 @@ pub struct FrameRecord {
 pub struct NewMessage {
     pub role:      Role,
     pub content:   String,
-    /// TIC/notify/injection: not echoed to the UI as a user message.
+    /// Event triage, notify, injection: not echoed to the UI as a user message.
     pub synthetic: bool,
     pub reasoning: Option<String>,
     /// Attachments, command display, … (host free-form).