fix(sim): real text-size scaling + correct joystick-board menu hint

Two more real-vs-sim mismatches, found after seeing the rendered UI:

1. The Clock screen's big time display (setTextSize(2)) rendered at size 1
   -- SimDisplayDriverCanvas ignored setTextSize() entirely (a leftover
   no-op from the old system-font renderer) and never overrode
   getCharWidth()/getLineHeight(), so the big-digit layout math in
   UITask.cpp's drawBig() came out wrong even once print() itself gained
   real font support. Track _text_sz, scale both metrics by it (matching
   SSD1306Display's own getCharWidth()==6*_text_sz pattern), and pass it
   through to miscFixedPrint() in target.cpp instead of a hardcoded 1.

2. The Home carousel's "<PRESS_LABEL> to open" hint said "long press to
   open" -- true only for touchscreen-only boards with no dedicated Enter
   button (PRESS_LABEL's #if UI_HAS_JOYSTICK / #else split in
   examples/companion_radio/ui-new/UITask.cpp). The sim's D-pad + OK key
   behaves like a joystick board (a SHORT Enter press opens each page;
   holding it separately reaches the real context menu via
   handleLongPress()), so showing the touchscreen wording was both
   inaccurate and different from what a real joystick board like Heltec V3
   displays. Added SIM_PLATFORM to that #if alongside UI_HAS_JOYSTICK --
   UI_HAS_JOYSTICK itself stays unset, since its other two gates
   (begin()-ing/polling real joystick MomentaryButton objects) need
   hardware the sim's target.cpp doesn't declare.

Verified in real Chromium: Clock screen shows "08:11:10" at real double
size above the normal-size date line; Home carousel now says "press Enter
to open". Full regression clean: 3 native envs, wasm companion_radio, the
2-instance+repeater mesh demo, and the long-press context-menu test.

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

examples/companion_radio/ui-new/UITask.cpp

@@ -50,7 +50,14 @@
   #define UI_RECENT_LIST_SIZE 4
 #endif
 
-#if UI_HAS_JOYSTICK
+// The sim's D-pad + dedicated OK/Enter key behaves like a joystick board
+// (a short Enter press opens Settings/Tools/Messages -- see the
+// KEY_ENTER && _page==... handlers below; holding it separately reaches
+// KEY_CONTEXT_MENU via handleLongPress(), same as a real joystick board's
+// long-press) -- without SIM_PLATFORM here, this would fall to the
+// touchscreen-board wording below, which describes a different, and for
+// this input method simply wrong, interaction.
+#if UI_HAS_JOYSTICK || defined(SIM_PLATFORM)
   #define PRESS_LABEL "press Enter"
 #else
   #define PRESS_LABEL "long press"