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>

scripts/check-reference.mjs

@@ -195,6 +195,7 @@ const ramNames = {
   curHPAnimDeltaHP: "wCurHPAnimDeltaHP",
   visitedSpawns: "wVisitedSpawns",
   tempWildMonSpecies: "wTempWildMonSpecies",
+  parkBallsRemaining: "wParkBallsRemaining",
   coins: "wCoins",
   bgMapMode: "hBGMapMode",
   blueCardBalance: "wBlueCardBalance",