⚡ replace polling timers with sorted event queues + action log

Crops, tree seedlings, and tile recovery no longer iterate all entries
every frame. Each event stores an absolute gameTime timestamp (growsAt).
A sorted priority queue is drained each tick — only due items are touched.

WorldState now tracks gameTime (ms); stateManager.advanceTime(delta)
increments it each frame. Save version bumped 5→6 with migration.

Action log ring buffer (15 entries) added to LocalAdapter; shown in
the F3 debug panel under "Last Actions".

Closes #36
Closes #37

src/scenes/UIScene.ts

@@ -463,6 +463,9 @@ export class UIScene extends Phaser.Scene {
       '',
       `Paths: ${data.activePaths} (cyan lines in world)`,
       '',
+      '── Last Actions ───────────────',
+      ...(data.actionLog.length > 0 ? data.actionLog : ['—']),
+      '',
       '[F3] close',
     ])
   }