Load the merged Strings catalog on FireRed boots

Game and Game2 hand the merged mod data to Strings.load right after the mod merge, so a translation mod's strings registry is what Strings() answers from. Game3:_loadMods did not: on a FireRed boot Strings() kept the catalog the launcher preloaded, which is every enabled mod's lang/strings.lua whatever game it targets, with no defined precedence, and never a registration made from mod code. Call Strings.load(self.data) after the merge, as the other two games do.

src/core/Game3.lua

@@ -223,6 +223,11 @@ function Game3:_loadMods(opts)
     require("src.core.Logger").error(
       "mods failed to load, continuing without them: %s", tostring(loader))
   end
+  -- After the merge, so a translation mod's catalog is what Strings() reads,
+  -- as Game (src/core/Game.lua) and Game2 do.  Without it the catalog the
+  -- launcher preloaded (every enabled mod's lang/strings.lua, whatever game
+  -- it targets) stayed in place for the whole FireRed session.
+  require("src.core.Strings").load(self.data)
   local okC, Gen3Compat = pcall(require, "src.mods.Gen3Compat")
   if okC and type(Gen3Compat) == "table" and Gen3Compat.applyMerged then
     local okA, err = pcall(Gen3Compat.applyMerged, self)

tests/game3_strings_catalog_test.lua

@@ -0,0 +1,37 @@
+#!/usr/bin/env luajit
+-- Game3 hands the merged mod data to Strings.load, like Game and Game2, so a
+-- translation mod's `strings` registry is what Strings() answers from.
+
+package.path = "./?.lua;./?/init.lua;" .. package.path
+love = require("tests.love_stub")
+
+local failed = 0
+local function check(cond, msg)
+  if not cond then
+    failed = failed + 1
+    print("[FAIL] " .. msg)
+  end
+end
+
+local merged = { YES = "OUI" }
+package.loaded["src.mods.Loader"] = {
+  new = function()
+    return {
+      load = function(_, data) data.strings = merged end,
+      status = function() return {} end,
+    }
+  end,
+}
+package.loaded["src.mods.Gen3Compat"] = { applyMerged = function() end }
+
+local Strings = require("src.core.Strings")
+Strings.load({ strings = { YES = "LAUNCHER" } }) -- the launcher's preload
+local Game3 = require("src.core.Game3")
+local game = { data = {} }
+Game3._loadMods(game, {})
+
+check(Strings("YES") == "OUI", "Strings() answers from the merged catalog after mods load")
+check(Strings("NO") == "NO", "an untranslated key still falls back to English")
+
+print(("game3_strings_catalog_test: %s (%d failed)"):format(failed == 0 and "PASS" or "FAIL", failed))
+if failed > 0 then os.exit(1) end