Port the special battle types and contest battles

Run the forced-shiny, trap, forced-item, Celebi, Suicune, roaming and Bug-Catching Contest battle types. Roaming battles keep their struct's DVs and HP byte, and every other battle makes CleanUpBattleRAM's roaming roll. The contest shows PARKBALL×, counts down Park Balls, ends when they run out, keeps its catch outside the party and asks before switching. Scripts load the special types with loadvar, and while a contest runs, encounters use BugCatchingContestBattleScript and ContestMons.

Validated with 596 unit tests, 155 browser tests (including the contest menu and switch screen), native/reference builds and reference/vendor/release checks. National Park's contest event, the roaming release and the Ilex Forest Celebi event come with their maps.

Closes #28

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

tests/battle-world.test.ts

@@ -37,6 +37,49 @@ function finish(world: GameWorld, action: "fight" | "run" = "fight") {
 }
 
 describe.skipIf(!existsSync(romPath))("world battle integration with the local ROM", () => {
+  it("runs a Bug-Catching Contest encounter through its battle script", () => {
+    const world = fixture("contest");
+    const party = structuredClone(world.state.party),
+      bag = structuredClone(world.state.bag);
+    // Pace on and off the test grass until the contest's 20% roll hits.
+    for (const direction of ENCOUNTER_WALK) if (!world.battle) world.move(direction);
+    for (let step = 0; step < 200 && !world.battle; step++) world.move(step % 2 ? "right" : "left");
+    expect(world.battle, world.diagnostic).toBeDefined();
+    const contest = world.state.bugContest!;
+    let asked = false;
+    const messages = new Set<string>();
+    for (let tick = 0; tick < 10000 && (world.battle || world.busy || world.dialogue); tick++) {
+      const view = world.battle;
+      if (!view) {
+        if (world.dialogue) world.advanceDialogue();
+        world.tick();
+        continue;
+      }
+      if (view.message) messages.add(view.message.text.replace(/\n/g, " "));
+      if (view.prompt?.kind === "action") {
+        expect(view.prompt.parkBalls).toBeGreaterThan(0);
+        world.battleAction({ action: "item", item: 0xb1, slot: -1 });
+      } else if (view.prompt?.kind === "contestswitch") {
+        asked = true;
+        expect(view.prompt.stock).toMatchObject({ name: "SCYTHER", level: 14 });
+        world.battleChoose(1);
+      } else if (view.message?.prompt) world.interact();
+      else world.tick();
+    }
+    expect(world.notice, world.diagnostic).toBe("");
+    // Committed once the script ended: one Park Ball per throw, the new
+    // catch in the contest, and the party and pack untouched.
+    const thrown = [...messages].filter((text) => text.includes("used the PARK BALL")).length;
+    expect(thrown, [...messages].join(" | ")).toBeGreaterThan(0);
+    expect(world.state.bugContest!.parkBalls).toBe(20 - thrown);
+    expect(world.state.bugContest!.parkBalls).toBeLessThan(20);
+    expect(asked).toBe(true);
+    expect(world.state.bugContest!.mon!.species).not.toBe(123);
+    expect(world.state.party).toEqual(party);
+    expect(world.state.bag).toEqual(bag);
+    expect(contest).not.toBe(world.state.bugContest);
+  });
+
   it("commits a victory, level-up, move learning and Pokédex sighting", () => {
     const world = fixture();
     encounter(world);