feat(nav): shared NavView — two-bearing navigate-to-point render helper

Phase 4. Header-only navview::draw() takes a target (lat, lon, label) plus
the caller's own fix and course-over-ground, and renders distance + two
absolute bearings (To / Hdg). Source-agnostic so Waypoints, Backtrack and
Nearby node nav all reuse it. Not wired in yet (phases 5-6).

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

examples/companion_radio/ui-new/NavView.h

@@ -0,0 +1,63 @@
+#pragma once
+// Shared "navigate to a point" view. The target is just a (lat, lon, label)
+// triple, so the same screen serves Waypoints, trail Backtrack and Nearby
+// node navigation. No magnetometer: we show two *absolute* bearings — the
+// target's bearing and the user's course over ground — and let the user
+// compare them ("target 145°, I'm heading 090° → bear right").
+//
+// Pure render helper; the caller supplies its own GPS fix + COG (from UITask).
+
+#include <helpers/ui/DisplayDriver.h>
+#include "../GeoUtils.h"
+
+namespace navview {
+
+// own_valid : is there a usable GPS fix for the device right now
+// cog_valid : is there a stable course-over-ground (UITask::currentCourse)
+inline void draw(DisplayDriver& d,
+                 bool own_valid, int32_t own_lat, int32_t own_lon,
+                 int32_t tgt_lat, int32_t tgt_lon,
+                 const char* label,
+                 bool cog_valid, int cog_deg) {
+  const int cx  = d.width() / 2;
+  const int hdr = d.headerH();
+
+  // Title bar: label, inverted (matches the Nearby/discover detail style).
+  char title[24];
+  d.translateUTF8ToBlocks(title, (label && label[0]) ? label : "Navigate", sizeof(title));
+  d.setColor(DisplayDriver::LIGHT);
+  d.fillRect(0, 0, d.width(), hdr - 1);
+  d.setColor(DisplayDriver::DARK);
+  d.drawTextEllipsized(2, 1, d.width() - 4, title);
+  d.setColor(DisplayDriver::LIGHT);
+  d.fillRect(0, hdr - 1, d.width(), d.sepH());
+
+  if (!own_valid) {
+    d.drawTextCentered(cx, hdr + (d.height() - hdr) / 2 - d.getLineHeight(), "No GPS fix");
+    return;
+  }
+
+  int   to_deg = geo::bearingDeg(own_lat, own_lon, tgt_lat, tgt_lon);
+  float dist_km = geo::haversineKm(own_lat, own_lon, tgt_lat, tgt_lon);
+  char dist[12];
+  geo::fmtDist(dist, sizeof(dist), dist_km);
+
+  const int step = d.lineStep();
+  int y = hdr + 2;
+
+  // Distance — emphasised at size 2.
+  d.setTextSize(2);
+  d.drawTextCentered(cx, y, dist);
+  y += d.getLineHeight() + 3;
+  d.setTextSize(1);
+
+  char line[20];
+  snprintf(line, sizeof(line), "To:  %d %s", to_deg, geo::bearingCardinal(to_deg));
+  d.drawTextLeftAlign(2, y, line); y += step;
+
+  if (cog_valid) snprintf(line, sizeof(line), "Hdg: %d %s", cog_deg, geo::bearingCardinal(cog_deg));
+  else           snprintf(line, sizeof(line), "Hdg: --");
+  d.drawTextLeftAlign(2, y, line); y += step;
+}
+
+}  // namespace navview