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/mcp/mod.rs

@@ -61,7 +61,7 @@ pub struct McpManager {
 
 /// Whether a runtime's server-pushed notifications are persisted to `mcp_events`.
 ///
-/// `mcp_events` is an **owner** table and its only consumer is TIC, which is
+/// `mcp_events` is an **owner** table and its only consumer is event triage, which is
 /// per-user: an event is something that happened to *someone*. The global
 /// runtime has no owner — its pool is `system.db` — so persisting there would
 /// produce rows nobody can attribute and nobody will ever read.