⚡ 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/NetworkAdapter.ts

@@ -8,12 +8,42 @@ export interface NetworkAdapter {
   onAction?: (action: GameAction) => void
 }
 
+const ACTION_LOG_SIZE = 15
+
 /** Singleplayer: apply actions immediately and synchronously */
 export class LocalAdapter implements NetworkAdapter {
   onAction?: (action: GameAction) => void
 
+  /** Ring-buffer of the last ACTION_LOG_SIZE dispatched action summaries. */
+  private _actionLog: string[] = []
+
   send(action: GameAction): void {
     stateManager.apply(action)
+    this._recordAction(action)
     this.onAction?.(action)
   }
+
+  /** Returns a copy of the recent action log (oldest first). */
+  getActionLog(): readonly string[] { return this._actionLog }
+
+  /**
+   * Appends a short summary of the action to the ring-buffer.
+   * @param action - The dispatched game action
+   */
+  private _recordAction(action: GameAction): void {
+    let entry = action.type
+    if ('tileX' in action && 'tileY' in action)
+      entry += ` (${(action as any).tileX},${(action as any).tileY})`
+    else if ('villagerId' in action)
+      entry += ` v=…${(action as any).villagerId.slice(-4)}`
+    else if ('resourceId' in action)
+      entry += ` r=…${(action as any).resourceId.slice(-4)}`
+    else if ('cropId' in action)
+      entry += ` c=…${(action as any).cropId.slice(-4)}`
+    else if ('seedlingId' in action)
+      entry += ` s=…${(action as any).seedlingId.slice(-4)}`
+
+    if (this._actionLog.length >= ACTION_LOG_SIZE) this._actionLog.shift()
+    this._actionLog.push(entry)
+  }
 }