Add active/inactive/game-time timers to fleet + server pages

Fleet cards and the per-server detail hero now show three live-ticking
timers: Active (since players > 0), Inactive (since server emptied), and
Game (since InitGame in games_sp.log, back-computed from the log's own
MM:SS prefix so it stays accurate across restarts). Anchors are
persisted on `servers` and fanned out via the SSE bus; a single 1s
ticker feeds every card. Idle map cycles are filtered out so the game
timer doesn't flicker.

src/lib/server/pipeline/bus.ts

@@ -18,6 +18,10 @@ export interface ServerStatusEntry {
     endpoint: RconEndpoint | null;
     reason: RconFailure | null;
     replySnippet: string | null;
+    activeSince: string | null;
+    inactiveSince: string | null;
+    gameStartedAt: string | null;
+    gameEndedAt: string | null;
 }
 
 export type BetaStage =