feat(outro): rètol "fase completada" en dues línies oposades

Mateixa tècnica que l'INTRO: la línia 1 ("Fase") entra per
l'esquerra, la línia 2 ("Completada") per la dreta, i surten cap
al costat oposat al d'entrada. Centrades verticalment al voltant
del CENTER_Y amb el gap configurable ( a
data/scenes/game.yaml; 0 per defecte, paral·lel a la del room_intro).

Locale: la clau game.room_complete es divideix en
game.room_complete_line1 / room_complete_line2 als ca.yaml i en.yaml
("Fase"/"Completada" i "Stage"/"Complete"). Cada línia es
tradueix per separat — útil si demà voleu paraules de longitud o
ordre distint en altres idiomes.

data/locale/en.yaml

@@ -36,15 +36,15 @@ hud:
   pyramid: "Pyramid"
   room: "Room"
 
-# Room transition texts (GameScene FSM intro/outro). The two pyramid /
-# room strings render as independent lines during INTRO (so they can
-# be animated separately in the future). They accept `{p}` (pyramid)
-# and `{r}` (room) placeholders, replaced with the current LevelManager
-# values.
+# Room transition texts (GameScene FSM intro/outro). Both INTRO and
+# OUTRO render as two independent lines with their own animation.
+# INTRO uses `{p}` (pyramid) and `{r}` (room) placeholders; OUTRO has
+# no placeholders — it's the two words of the "stage complete" label.
 game:
   room_intro_pyramid: "Pyramid {p}"
   room_intro_room: "Room {r}"
-  room_complete: "Stage complete"
+  room_complete_line1: "Stage"
+  room_complete_line2: "Complete"
 
 menu:
   titles: