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/compactor.rs

@@ -11,7 +11,7 @@
 //! It is a stateless service (all state lives in the DB), shared via `Arc`
 //! across every [`ChatSessionHandler`](crate::session::handler). Triggered at
 //! the **start of a turn** when the previous turn's `input_tokens` exceeded the
-//! threshold, or manually via `force_compact`. Ephemeral sessions (cron, tic)
+//! threshold, or manually via `force_compact`. Ephemeral sessions (cron, event-triage)
 //! are always skipped.
 //!
 //! ```text