Cover Gold's Light Screen / Reflect fix in the same test

The targeted test only covered the RBY side (ItemEffects.lua,
TrainerAI.lua); src/battle/gen2/Battle.lua's EFFECT_LIGHT_SCREEN/
EFFECT_REFLECT fix had no test at all, spotted when asked whether the
Gold changes were covered.

Adds a minimal MACHOP/TACKLE gen2 fixture (same shape as
tests/gen2_move_effects_test.lua's), calls both MOVE_EFFECTS directly,
and checks a loaded catalog reaches the whole message template (Gold
wraps the full sentence, not just the stat name). Confirmed it catches
the regression: reverting Battle.lua to its pre-fix state fails 2 of
the suite's now 8 checks.

tests/engine/stat_rise_message_translation_test.lua

@@ -1,12 +1,13 @@
--- The stat name substituted into X-item/vitamin "rose!" messages must
--- itself reach a translation catalog, not just the surrounding sentence
--- template (src/inventory/ItemEffects.lua, src/battle/TrainerAI.lua).
--- With no catalog loaded it stays English (the existing baseline); with
--- one loaded that translates e.g. "ATTACK", the substituted word must
--- change too -- that is the actual bug this suite guards against, which
--- passing/failing sentences alone (as other suites already check)
--- cannot tell apart from a raw stat:upper() that was never wrapped in
--- Strings() at all.
+-- The stat name substituted into X-item/vitamin "rose!" messages, and
+-- Gold's whole Light Screen / Reflect "rose!" messages, must reach a
+-- translation catalog, not just the surrounding sentence template (RBY:
+-- src/inventory/ItemEffects.lua, src/battle/TrainerAI.lua; Gold:
+-- src/battle/gen2/Battle.lua). With no catalog loaded the message stays
+-- English (the existing baseline); with one loaded that translates the
+-- relevant word(s), the substitution must change too -- that is the
+-- actual bug this suite guards against, which passing/failing sentences
+-- alone (as other suites already check) cannot tell apart from text that
+-- never reached Strings() at all.
 package.path = "./?.lua;./?/init.lua;" .. package.path
 
 local T = require("tests.modkit")
@@ -70,4 +71,71 @@ withCatalog({ SPEED = "VITESSE" }, function()
     "a catalog translating SPEED reaches the AI trainer's X SPEED rose! message")
 end)
 
+-- ------------------------------------------------------- Gold: Light Screen / Reflect
+
+local Gen2Battle = require("src.battle.gen2.Battle")
+local Gen2Mon = require("src.battle.gen2.Mon")
+
+local GEN2_DATA = {
+  pokemon = {
+    MACHOP = {
+      id = "MACHOP", index = 66, name = "MACHOP",
+      baseStats = { hp = 70, attack = 80, defense = 50, speed = 35,
+        specialAttack = 35, specialDefense = 35 },
+      types = { "NORMAL", "NORMAL" }, catchRate = 180, baseExp = 75,
+      growthRate = "GROWTH_MEDIUM_FAST", genderRatio = 63,
+      levelMoves = { { level = 1, move = "TACKLE" } }, evolutions = {},
+    },
+  },
+  moves = {
+    TACKLE = { id = "TACKLE", name = "TACKLE", power = 35, type = "NORMAL",
+      accuracy = 95, pp = 35, effect = "EFFECT_NORMAL_HIT" },
+  },
+  type_chart = { types = { NORMAL = { id = "NORMAL", index = 0,
+    category = "physical" } }, matchups = {} },
+  items = {},
+}
+local perfectDvs = { attack = 15, defense = 15, speed = 15, special = 15 }
+perfectDvs.hp = Gen2Mon.hpDV(perfectDvs)
+
+local function newGen2Battle()
+  local player = Gen2Mon.new(GEN2_DATA, "MACHOP", 15, { dvs = perfectDvs })
+  player.moves = { { id = "TACKLE", pp = 35, maxPp = 35 } }
+  local wild = Gen2Mon.new(GEN2_DATA, "MACHOP", 15, { dvs = perfectDvs })
+  wild.moves = { { id = "TACKLE", pp = 35, maxPp = 35 } }
+  return Gen2Battle.new({ data = GEN2_DATA, party = { player }, wild = wild })
+end
+
+withCatalog({ ["%s's SPCL.DEF rose!"] = "%s voit sa DEF.SPÉ augmenter !" },
+  function()
+    local lsBattle = newGen2Battle()
+    Gen2Battle.MOVE_EFFECTS.EFFECT_LIGHT_SCREEN(lsBattle, lsBattle.player)
+    local events = lsBattle:takeEvents()
+    local found = false
+    for _, event in ipairs(events) do
+      if event.kind == "message"
+          and event.text:find("DEF.SPÉ augmenter", 1, true) then
+        found = true
+      end
+    end
+    T.check(found,
+      "a catalog translating Light Screen's rose! message reaches it")
+  end)
+
+withCatalog({ ["%s's DEFENSE rose!"] = "%s voit sa DEFENSE augmenter !" },
+  function()
+    local refBattle = newGen2Battle()
+    Gen2Battle.MOVE_EFFECTS.EFFECT_REFLECT(refBattle, refBattle.player)
+    local events = refBattle:takeEvents()
+    local found = false
+    for _, event in ipairs(events) do
+      if event.kind == "message"
+          and event.text:find("DEFENSE augmenter", 1, true) then
+        found = true
+      end
+    end
+    T.check(found,
+      "a catalog translating Reflect's rose! message reaches it")
+  end)
+
 T.finish("stat rise message translation")