Port Headbutt and Rock Smash encounters

Facing a Headbutt tree asks to HEADBUTT it, and HEADBUTT from the party
menu skips the question. ShakeHeadbuttTree shakes the tree as a sprite over
grass, then TreeMonEncounter scores the facing tile against the trainer ID
and draws from the map's common or rare tree table. A Pokémon that falls
fights as BATTLETYPE_TREE: "fell out of the tree!", and the time of day's
AsleepTreeMons species start asleep.

Smashable rocks run SmashRockScript, and ROCK SMASH from the party menu
acts on the facing rock; after the rock breaks, RockMonEncounter gives the
map's rock set a 40% chance of a wild battle.

Closes #26

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/game/world/world.ts

@@ -551,7 +551,12 @@ const isTimed = (effect: ScriptEffect | undefined) =>
   effect?.kind === "move" ||
   effect?.kind === "emote" ||
   effect?.kind === "pause" ||
-  effect?.kind === "fly";
+  effect?.kind === "fly" ||
+  effect?.kind === "headbutt";
+/** ShakeHeadbuttTree after its graphics load: HideHeadbuttTree's WaitBGMap
+ * (4 frames), 32 frames of shaking, then the WaitBGMap that restores the
+ * tree, 40 frames in all. */
+const HEADBUTT_TICKS = 20;
 
 /** Deterministic native world rules. Rendering, browser APIs and emulator
  * registers are deliberately absent; callers provide time and input. */
@@ -639,6 +644,9 @@ export class GameWorld {
   private warpSettle?: { script?: number };
   /** FlyFromAnim or FlyToAnim while it plays, with the frames shown. */
   private flight?: { landing: boolean; species: number; frames: number };
+  /** ShakeHeadbuttTree while it plays: the facing square and the frames
+   * shown. */
+  private shakingTree?: { x: number; y: number; frames: number };
 
   constructor(
     readonly assets: CrystalAssets,
@@ -828,6 +836,12 @@ export class GameWorld {
     };
   }
 
+  /** The tree ShakeHeadbuttTree shakes: its map square and the video
+   * frames since the shaking sprite appeared. */
+  get headbuttTree(): { x: number; y: number; frames: number } | undefined {
+    return this.shakingTree && { ...this.shakingTree };
+  }
+
   /** Pixel positions for drawing, including partial steps. */
   poses(): Pose[] {
     // HideSprites and the Fly animations' loops leave only their icon.
@@ -1697,12 +1711,19 @@ export class GameWorld {
       case OW.HEADBUTT:
         return tile === OW.COLL_HEADBUTT_TREE ||
           tile === OW.COLL_HEADBUTT_TREE_1D
-          ? { notice: "Headbutt trees are not ported yet." }
+          ? { script: OVERWORLD.HeadbuttFromMenuScript, fieldMove: { mon } }
           : failed;
-      case OW.ROCK_SMASH:
-        return facingObject()?.movement === OW.SPRITEMOVEDATA_SMASHABLE_ROCK
-          ? { notice: "Smashing rocks is not ported yet." }
+      case OW.ROCK_SMASH: {
+        // GetFacingObject leaves the rock in hLastTalked.
+        const rock = facingObject();
+        return rock?.movement === OW.SPRITEMOVEDATA_SMASHABLE_ROCK
+          ? {
+              script: OVERWORLD.RockSmashFromMenuScript,
+              fieldMove: { mon },
+              lastTalked: rock.id,
+            }
           : failed;
+      }
       case OW.SWEET_SCENT: {
         // SweetScentEncounter, drawn now: no rate roll, and no battle
         // without a rate or a valid Pokémon.
@@ -2307,6 +2328,7 @@ export class GameWorld {
           wild: effect.wild,
           trainer,
           canLose: effect.canLose,
+          tree: effect.tree,
           text: () => this.host(PLAYER).text(),
           bag: draft.bag,
           storage: draft.storage,
@@ -2350,6 +2372,16 @@ export class GameWorld {
         this.flight = { ...effect, frames: 0 };
         script.waitTicks = effect.landing ? 33 : 65;
         return true;
+      case "headbutt": {
+        const [dx, dy] = VECTORS[this.player.direction];
+        this.shakingTree = {
+          x: this.player.x + dx,
+          y: this.player.y + dy,
+          frames: 0,
+        };
+        script.waitTicks = HEADBUTT_TICKS;
+        return true;
+      }
       case "warpcheck":
         script.warpCheck = true;
         return false;
@@ -2858,7 +2890,9 @@ export class GameWorld {
     if (script.run.deferred !== undefined)
       this.startScript(
         script.run.deferred,
-        PLAYER,
+        (script.run instanceof StartMenuRun &&
+          script.run.deferredMove?.lastTalked) ||
+          PLAYER,
         script.run instanceof StartMenuRun
           ? {
               usedItem: script.run.deferredItem,
@@ -2890,6 +2924,7 @@ export class GameWorld {
     this.portrait = undefined;
     this.evolution = undefined;
     this.flight = undefined;
+    this.shakingTree = undefined;
     if (script.sighted !== undefined)
       this.refusedSighting = {
         map: this.mapId,
@@ -3402,13 +3437,15 @@ export class GameWorld {
         else this.advanceMovement(1);
       } else if (isTimed(script.effect)) {
         // Pauses and emotes keep the map loop running; applymovement and
-        // open text freeze other objects, and the Fly animations run their
-        // own loops.
+        // open text freeze other objects, and the Fly animations and the
+        // Headbutt shake run their own loops.
         if (this.flight) this.flight.frames += 2;
+        else if (this.shakingTree) this.shakingTree.frames += 2;
         else this.stepObjects();
         if (--script.waitTicks <= 0) {
           if (script.effect?.kind === "emote") this.emote = undefined;
           this.flight = undefined;
+          this.shakingTree = undefined;
           this.pump();
         }
       }
@@ -3649,10 +3686,12 @@ export class GameWorld {
       return true;
     }
     if (tile === OW.COLL_HEADBUTT_TREE || tile === OW.COLL_HEADBUTT_TREE_1D) {
-      // TryHeadbuttOW: without Headbutt nothing happens; tree encounters
-      // (TreeMonEncounter) are not ported.
-      if (this.partyMove(OW.HEADBUTT) < 0) return false;
-      this.notice = "Headbutt trees are not ported yet.";
+      // TryHeadbuttOW: without Headbutt nothing happens.
+      const mon = this.partyMove(OW.HEADBUTT);
+      if (mon < 0) return false;
+      this.startScript(OVERWORLD.AskHeadbuttScript, PLAYER, {
+        fieldMove: { mon },
+      });
       return true;
     }
     return this.trySurfOW(tile);