Fix duplicate class and annotation placement lint errors

Classes contributed to by more than one file now carry the `partial`
attribute. trains.lua declared its command as `ExpCommand_Artillery`,
which was a copy paste.

`Color.0` and `MapPosition.0` became `.struct` in fmtk 2.1.6.

emmylua rejects `@type` on a function statement or a `do` block, so
those are moved onto the local or replaced by `@param` and `@return`.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

exp_scenario/module/gui/elements.lua

@@ -25,8 +25,7 @@ Elements.online_player_dropdown = Gui.define("player_dropdown")
     } --[[ @as any ]]
 
 --- To help with caching and avoid context changes the player list from the previous update is remembered
---- @type (string?)[]
-do local _player_names = {}
+do local _player_names = {} --- @type (string?)[]
     --- Updates the player name list after a join or leave
     --- @return (string?)[]
     function Elements.online_player_dropdown._update_player_names()