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>

scripts/check-reference.mjs

@@ -190,6 +190,7 @@ const ramNames = {
   strengthSpecies: "wStrengthSpecies",
   curHPAnimDeltaHP: "wCurHPAnimDeltaHP",
   visitedSpawns: "wVisitedSpawns",
+  tempWildMonSpecies: "wTempWildMonSpecies",
   moneyTemp: "hMoneyTemp",
 };
 const profile = readFileSync("src/game/rom/profile.ts", "utf8");