refactor(ui): shared drawList + header + key-decode helpers

- drawList(): scrollable list skeleton (visible window, keep-sel-in-view,
  scroll-column reserve, per-row callback, indicator). Migrate Tools, Bot,
  Nearby, Waypoints list and the three QuickMsg lists onto it; centralises the
  scroll-clamp/reserve/indicator that each had open-coded (and inconsistently).
- drawCenteredHeader(): centred title + separator, replacing the duplicated
  two-liner across ~10 screens (incl. QuickMsg, which used width()/2 spacing and
  was missed before); unifies the separator at headerH()-sepH().
- keyIsPrev()/keyIsNext() in UIScreen.h for the LEFT||PREV / RIGHT||NEXT idiom;
  applied to 6 screens, behaviour-preserving. Cancel/context-menu stay
  per-screen (they mean different things on different screens).
- rotLabel() dedups the 0/90/180/270 array in Settings.
- Unify selection-row height to lineStep()-1 (Tools/Bot matched the rest).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

examples/companion_radio/ui-new/icons.h

@@ -276,6 +276,28 @@ inline void drawScrollIndicator(DisplayDriver& d, int top_y, int track_h,
   miniIconDrawHalo(d, x, top_y + track_h - th, ICON_SCROLL_DOWN);
 }
 
+// Scrollable item-list skeleton shared by the list screens. Computes the visible
+// window from the font metrics, keeps `sel` in view, reserves the scroll-column,
+// draws each visible row through `row`, then the indicator. The callback
+// `row(idx, y, sel, reserve)` draws one item — including its own selection bar —
+// using `reserve` to keep right-aligned content clear of the indicator. Returns
+// the visible row count (callers cache it for input handling).
+template <class RenderRow>
+inline int drawList(DisplayDriver& d, int total, int sel, int& scroll, RenderRow row) {
+  const int item_h  = d.lineStep();
+  const int start_y = d.listStart();
+  int visible = d.listVisible(item_h);
+  if (visible < 1) visible = 1;
+  if (sel < scroll)            scroll = sel;
+  if (sel >= scroll + visible) scroll = sel - visible + 1;
+  if (scroll < 0) scroll = 0;
+  const int reserve = scrollIndicatorReserve(d, total, visible);
+  for (int i = 0; i < visible && (scroll + i) < total; i++)
+    row(scroll + i, start_y + i * item_h, scroll + i == sel, reserve);
+  drawScrollIndicator(d, start_y, visible * item_h, total, visible, scroll);
+  return visible;
+}
+
 // ── Big ASCII-art icons (skeleton, not yet used) ─────────────────────────────
 // Same authoring idea as the mini-icons but for full page glyphs up to 32 px
 // wide: one uint32_t per row. The existing XBM bitmaps below (logo/bluetooth/…)