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/control/discord_alerts.lua

@@ -39,7 +39,7 @@ local function get_player_name(event)
 end
 
 --- Convert a colour value into hex
---- @param color Color.0
+--- @param color Color.struct
 --- @return string
 local function to_hex(color)
     local hex_digits = "0123456789ABCDEF"
@@ -53,7 +53,7 @@ local function to_hex(color)
 end
 
 --- Emit the requires json to file for the given event arguments
---- @param opts { title: string?, color: (Color.0 | string)?, description: string?, tick: number?, fields: { name: string, value: string, inline: boolean? }[] }
+--- @param opts { title: string?, color: (Color.struct | string)?, description: string?, tick: number?, fields: { name: string, value: string, inline: boolean? }[] }
 local function emit_event(opts)
     local admins_online = 0
     local players_online = 0

exp_scenario/module/control/spawn_area.lua

@@ -7,7 +7,7 @@ local config = require("modules.exp_legacy.config.spawn_area")
 --- Apply an offset to a LuaPosition
 --- @param position MapPosition
 --- @param offset MapPosition
---- @return MapPosition.0
+--- @return MapPosition.struct
 local function apply_offset(position, offset)
     return {
         x = (position.x or position[1]) + (offset.x or offset[1]),