Clarify touch gesture and input API comments

Simplify and clarify documentation for touch gesture detection (back gesture, item taps, long-press) and board detection flags. No functional changes, just improved comment readability.

src/components/TouchRegistry.h

@@ -8,15 +8,10 @@
 #include "components/themes/BaseTheme.h"  // Rect
 
 // Frame-scoped registry of tappable UI elements. Theme draw methods record each
-// interactive element's LOGICAL rect + id during render() (on the render task);
-// the input layer hit-tests a tap against it during the next loop() (main task).
-//
-// Lock-free single-writer (render) / single-reader (loop) via double buffering:
-// render writes the back buffer and publish() atomically flips it to live, so the
-// reader never observes a half-built frame. No per-frame heap allocation.
-//
-// Runtime-gated: disabled on boards without touch (setEnabled(gpio.hasTouch())),
-// so add()/hitTest() are a single branch on the C3.
+// element's logical rect + id during render() (render task); the input layer
+// hit-tests a tap in the next loop() (main task). Lock-free via double buffering:
+// render writes the back buffer, publish() flips it live. No per-frame heap.
+// Runtime-gated off on boards without touch (setEnabled).
 class TouchRegistry {
  public:
   enum Kind : uint8_t { Item = 0, Back = 1, Tab = 2, Cover = 3 };

src/components/themes/BaseTheme.cpp

@@ -355,9 +355,7 @@ void BaseTheme::drawList(const GfxRenderer& renderer, Rect rect, int itemCount,
 }
 
 void BaseTheme::drawHeader(const GfxRenderer& renderer, Rect rect, const char* title, const char* subtitle) const {
-  // Left strip of the header is a tap-to-go-back zone (orientation-mapped; the
-  // title is centered so this area is normally empty). Mirrors the legacy corner
-  // gesture but as a real, theme-positioned target.
+  // Left strip of the header is a tap-to-go-back zone (title is centered, so it's empty).
   TouchRegistry::getInstance().add(Rect{rect.x, rect.y, 64, rect.height + 8}, -1, TouchRegistry::Back);
 
   // Hide last battery draw