Fix Gen 1/2 battle, menu, PC and audio parity gaps; wire luacheck into CI

CLOSES #1484, CLOSES #1486, CLOSES #1513, CLOSES #1517, CLOSES #1556, CLOSES #1564, CLOSES #1567

src/mods/Gen2Compat.lua

@@ -808,6 +808,31 @@ local function buildOverworld()
   local Movement = rawRequire("src.script.gen2.Movement")
   local HiddenItems = rawRequire("src.world.gen2.HiddenItems")
   local Bike = rawRequire("src.world.gen2.Bike")
+  local FieldMoves = rawRequire("src.world.gen2.FieldMoves")
+
+  -- home/map.asm:1869
+  local function stepAllowed(world, entity, dir)
+    local d = Map2.DELTA[dir]
+    if not (world.map and d and entity and entity.cellX) then return true end
+    if not Permissions.stepPermitted(
+         function(cx, cy) return world:cellCollisionAcross(world.map, cx, cy) end,
+         entity.cellX, entity.cellY, dir) then
+      return false
+    end
+    local map = world.map
+    if entity == world.player and FieldMoves.isSurfing(world.playerState) then
+      map = world:surfMap(world.map)
+    end
+    local tx, ty = entity.cellX + d[1], entity.cellY + d[2]
+    if not map:inBounds(tx, ty) or not map:isWalkable(tx, ty) then return false end
+    for _, e in ipairs(world.entities or {}) do
+      if e ~= entity and not e.passable then
+        if e.cellX == tx and e.cellY == ty then return false end
+        if e.moving and e.targetX == tx and e.targetY == ty then return false end
+      end
+    end
+    return true
+  end
 
   local api = nil
   -- one WorldAPI instance, so queueScript reuses the five-verb allow list
@@ -1011,20 +1036,25 @@ local function buildOverworld()
 
   -- Gold has ONE movement slot; a second concurrent call is refused with a
   -- reason rather than dropped (src/world/gen2/WorldAPI.lua:171's recipe).
-  function ow.scriptMove(entity, dir, tiles, onDone)
+  function ow.scriptMove(entity, dir, tiles, onDone, opts)
     local world = w("scriptMove")
     if not world then return nil, "no overworld" end
     if world.moveState then return nil, "a movement is already running" end
     local step = Movement.stepByte(dir)
     if not step then return nil, "unknown direction: " .. tostring(dir) end
-    local bytes = {}
-    for _ = 1, math.max(0, tiles or 1) do bytes[#bytes + 1] = step end
-    bytes[#bytes + 1] = Movement.STEP_END
     local objectId = objectIdOf(world, entity)
     if not objectId then
       return nil, "no Gen 2 objectId for that entity: only the player and a "
         .. "mapped object (def.index) can be moved"
     end
+    local n = math.max(0, tiles or 1)
+    if opts and opts.collide and n > 0 and not stepAllowed(world, entity, dir) then
+      entity.facing = dir
+      n = 0
+    end
+    local bytes = {}
+    for _ = 1, n do bytes[#bytes + 1] = step end
+    bytes[#bytes + 1] = Movement.STEP_END
     world:beginMovement(objectId, bytes, onDone)
     return true
   end

src/mods/Loader.lua

@@ -119,6 +119,17 @@ local GEN1_ONLY_MODULES = {
   ["src.ui.OptionsMenu"] = true,
 }
 
+local function crossGenerationDenial(name, generation)
+  if type(name) ~= "string" or generation ~= 1 then return nil end
+  if not (name:find("^src%.[%w_]+%.gen2%.") or name == "src.core.Game2") then
+    return nil
+  end
+  return ("%s is a Gen 2 engine module and this is a Gen 1 game; the structs "
+    .. "it reads and writes are not this game's, so anything it stores lands "
+    .. "on the save in the wrong shape. Take the game from mod.game and the "
+    .. "world from mod.world, which resolve per generation"):format(name)
+end
+
 -- the src.* modules the mod surface points authors at: another mod's
 -- exports carry a version string that wants range-checking before use, and
 -- ChipAsm is the authoring path for chip music and sfx
@@ -214,6 +225,7 @@ function Loader:_installDevShim()
       if owner or callerIsMod(3) then
         local id = type(owner) == "string" and owner or nil
         local denial = Sandbox.moduleDenial(name, devShim.permissions[id])
+          or (id and crossGenerationDenial(name, devShim.generation))
         if denial then error(("[%s] %s"):format(id or "mod", denial), 0) end
       end
       if devShim.dev or devShim.generation ~= 1 then scanRequire(name) end