Clock: show it at once and render it cheaply; Guide is KEY_GUIDE

The remote's hauppauge.rem names the Guide button KEY_GUIDE, not lircd's
KEY_EPG, so the remote never toggled the clock.

The overlay is now hidden by opacity rather than display: none, so it is
already laid out and painted when Pos1 or Guide shows it. The drop-shadow
filter on the whole watch is gone (it re-rendered and re-blurred the dial on
every second-hand tick), the hands sit on their own layers, and the bubbles
and countdown cards only exist while the clock is on screen.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

python-backend/musicmouse/services/lirc/service.py

@@ -47,8 +47,10 @@ _TRANSPORT: dict[str, Callable[[], IntentEvent]] = {
     "KEY_FORWARD": lambda: NextTrackRequested(source="lirc"),
     # Does nothing unless general.screen is configured - see ScreenService.
     "KEY_POWER": lambda: ToggleScreenRequested(source="lirc"),
-    # "Guide": what time is it. Shows the kiosk's clock overlay.
-    "KEY_EPG": lambda: ToggleClockRequested(source="lirc"),
+    # "Guide": what time is it. Shows the kiosk's clock overlay. KEY_GUIDE is what
+    # irserver's hauppauge.rem calls it (the ansible repo); lircd's own Hauppauge
+    # config says KEY_EPG.
+    "KEY_GUIDE": lambda: ToggleClockRequested(source="lirc"),
 }
 
 #: Acted on every repeat, for a continuous ramp while held - same feel as the rotary