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-browser.spec.ts

@@ -34,6 +34,18 @@ async function start(page: Page, scenario: BattleScenario = "win") {
     await page.keyboard.up(key);
     await page.clock.runFor(300);
   }
+  if (scenario === "contest") {
+    // The contest's 20% roll: pace on and off the test grass.
+    for (let step = 0; step < 100 && !(await page.locator("#battle").isVisible()); step++) {
+      const key = step % 2 ? "ArrowRight" : "ArrowLeft";
+      await page.keyboard.down(key);
+      await page.clock.runFor(250);
+      await page.keyboard.up(key);
+      await page.clock.runFor(300);
+    }
+    await expect(page.locator("#battle")).toBeVisible();
+    return;
+  }
   await expect(page.locator("#battle")).toBeVisible();
   await expect(page.locator("#battle-foe-name")).toHaveText("PIDGEY");
 }
@@ -300,3 +312,34 @@ test("battle PKMN STATS shows the stats screen's three pages and returns with B"
   // BattleMenuPKMN_ReturnFromStats: back to the party menu.
   await expect(menu.getByRole("button", { name: /^CYNDAQUIL/ })).toBeVisible();
 });
+
+test("throws Park Balls from the contest menu and switches the stocked Pokémon", async ({ page }) => {
+  await start(page, "contest");
+  const menu = page.locator("#battle-menu");
+  let balls = 20,
+    switched = false;
+  const texts: string[] = [];
+  for (let guard = 0; guard < 200 && (await page.locator("#battle").isVisible()); guard++) {
+    texts.push(await page.locator("#battle-text").innerText());
+    const ball = menu.getByRole("button", { name: /^PARKBALL×\d\d$/ });
+    if (await ball.count()) {
+      // ContestBattleMenu replaces PACK, with the count in two digits.
+      await expect(ball).toHaveText(`PARKBALL×${String(balls).padStart(2, "0")}`);
+      await expect(menu.getByRole("button", { name: "PACK" })).toHaveCount(0);
+      await ball.click();
+      balls--;
+    } else if (await menu.getByRole("button", { name: /^STOCK SCYTHER :L14/ }).count()) {
+      await expect(menu.getByRole("button", { name: /^THIS / })).toBeVisible();
+      await expect(page.locator("#battle-text")).toContainText("Switch");
+      // The cursor skips the two boxes: down to NO, back up to YES, then A.
+      await page.keyboard.press("ArrowDown");
+      await page.keyboard.press("ArrowUp");
+      await page.keyboard.press("KeyX");
+      switched = true;
+    } else if (await menu.getByRole("button", { name: /Continue/ }).count())
+      await menu.getByRole("button", { name: /Continue/ }).click();
+    else await page.clock.runFor(1200);
+  }
+  expect(switched, texts.join(" | ")).toBe(true);
+  expect(texts.join(" ").replace(/\n/g, " ")).toMatch(/Caught [A-Z]+!/);
+});