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/skald/user_context.rs

@@ -242,7 +242,7 @@ impl UserContextFactory {
             user_shutdown.clone(),
             "data",
             // This user's connectors push into this user's `mcp_events`, which is
-            // what TIC reads on their behalf.
+            // what event triage reads on their behalf.
             crate::mcp::EventLog::Persist,
         ));
         // NOTE: per-user MCP elicitation (interactive connector login, §15) is