Route remaining hardcoded UI strings through the locale system

Main menu buttons, the confirm dialog, battle menu/HUD text, backpack
tab labels, the loading/autosave indicators, and the settings tab
placeholders were all raw English literals bypassing translation.
Loads each through assetLocaleGetString like the rest of the UI, adding
new Init hooks for uibattlehud/uiautosave/uiloading where none existed,
and adds the corresponding message ids to en_US/es_MX/jp_JP.po.

Also widens the settings placeholder buffers to 64 bytes - the es_MX
and jp_JP translations overflowed the previous 32-byte size.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

assets/locale/es_MX.po

@@ -113,6 +113,74 @@ msgstr "Sí"
 msgid "ui.initial.create_save.no"
 msgstr "No"
 
+#: src/dusk/ui/frame/mainmenu/uimainmenu.c
+msgid "ui.main_menu.new_game"
+msgstr "Nueva Partida"
+
+#: src/dusk/ui/frame/mainmenu/uimainmenu.c
+msgid "ui.main_menu.load_game"
+msgstr "Cargar Partida"
+
+#: src/dusk/ui/frame/mainmenu/uimainmenu.c
+msgid "ui.main_menu.options"
+msgstr "Opciones"
+
+#: src/dusk/ui/frame/mainmenu/uimainmenu.c
+msgid "ui.main_menu.quit"
+msgstr "Salir del Juego"
+
+#: src/dusk/ui/frame/uiconfirm.c
+msgid "ui.confirm.confirm"
+msgstr "Confirmar"
+
+#: src/dusk/ui/frame/uiconfirm.c
+msgid "ui.confirm.cancel"
+msgstr "Cancelar"
+
+#: src/dusk/ui/frame/battle/uibattlemenu.c
+msgid "ui.battle.menu.attack"
+msgstr "Atacar"
+
+#: src/dusk/ui/frame/battle/uibattlemenu.c
+msgid "ui.battle.menu.flee"
+msgstr "Huir"
+
+#: src/dusk/ui/frame/battle/uibattlemenu.c
+msgid "ui.battle.menu.target_format"
+msgstr "Enemigo %u (%u/%u PS)"
+
+#: src/dusk/ui/frame/battle/uibattlehud.c
+msgid "ui.battle.hud.hp_format"
+msgstr "PS %u/%u"
+
+#: src/dusk/ui/frame/battle/uibattlehud.c
+msgid "ui.battle.hud.mp_format"
+msgstr "PM %u/%u"
+
+#: src/dusk/ui/frame/settings/uisettingsaudio.c
+msgid "ui.settings.audio.placeholder"
+msgstr "Aún no hay opciones de audio"
+
+#: src/dusk/ui/frame/settings/uisettingsdisplay.c
+msgid "ui.settings.display.placeholder"
+msgstr "Aún no hay opciones de pantalla"
+
+#: src/dusk/ui/frame/settings/uisettingsinput.c
+msgid "ui.settings.input.placeholder"
+msgstr "Aún no hay opciones de entrada"
+
+#: src/dusk/ui/frame/backpack/uibackpack.c
+msgid "ui.backpack.category_format"
+msgstr "Categoría %u"
+
+#: src/dusk/ui/overlay/uiloading.c
+msgid "ui.loading.text"
+msgstr "cargando"
+
+#: src/dusk/ui/overlay/uiautosave.c
+msgid "ui.autosave.saving"
+msgstr "GUARDANDO"
+
 #: src/dusk/rpg/item/item.json
 msgid "item.potion.name"
 msgstr "Poción"