feat(box): celebratory spinning star on bravo

Make the end-of-routine "Bravo !" lively: the star now spins
(continuous full turn via lv_image_set_rotation) and bounces
(translate_y ping-pong). Both use layer-free paths — image
rotation transforms against the flush band, translate is not a
layer-forcing style — so the render task stays light (no repeat
of the full-screen-layer task_wdt). Auto-return stretched to
3.6 s so the spin shows and the festive cue finishes.

Tower: seed a more festive bravo.mp3 line ("Youpi, tu as
réussi ! Tu es super !").

tower/lisael_content.py

@@ -165,7 +165,7 @@ def build_routine_manifest(gen_bin=None, gen_audio=None):
     # Seed fixed firmware sound cues (only on the real TTS path, not in test fakes)
     if _real_audio:
         _seed_fixed_sound("ok.mp3", "Et hop !")
-        _seed_fixed_sound("bravo.mp3", "Bravo ! Tu as fini.")
+        _seed_fixed_sound("bravo.mp3", "Bravo ! Youpi, tu as réussi ! Tu es super !")
     return {"generated": generated, "skipped": skipped, "routines": manifest}
 
 def _gen_step_audio(text, key):