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/skald-core/src/chat_hub/mod.rs

@@ -50,11 +50,11 @@ const SOURCE_COALESCE_DEBOUNCE_MS: u64 = 0;
 /// one live, persistent session per `source`, reachable over WebSocket and addressed
 /// by source id through the `sources` table.
 ///
-/// It is **not** a runner for background / non-interactive agents (cron jobs, TIC,
-/// sub-agent tasks). Those go through `TaskManager` / `ChatSessionManager` directly and
-/// must not be routed here — they are not user-facing, have no broadcast audience, and
-/// should not appear in the `sources` table. (Historically this class was misused to
-/// drive non-interactive agents; keep that boundary.)
+/// It is **not** a runner for background / non-interactive agents (cron jobs, event
+/// triage, sub-agent tasks). Those go through `TaskManager` / `ChatSessionManager`
+/// directly and must not be routed here — they are not user-facing, have no broadcast
+/// audience, and should not appear in the `sources` table. (Historically this class was
+/// misused to drive non-interactive agents; keep that boundary.)
 pub struct ChatHub {
     db:          Arc<SqlitePool>,
     session_mgr: Arc<ChatSessionManager>,