refactor(ui): remove dead code and fix stale comments after the review

- ui-core: Diagnostics::systemLines, NearbyModel::typeShort,
  rptctl::currentPresetName, RoomSessions::pendingKey, settings::isSwitch,
  UiCore::reconcileDMUnread.
- ui-new: the retired Recent page, fmtAlt, the battMvToPercent wrapper,
  setFavouriteChannelSlot, AccordionList onHeader/visibleCount, drawBoxedIcon
  and seven unused icons; info::row folded into info::valueRow.
- ui-lvgl: onOpenNav, TileDownloader::withTrails; the trail header size is
  one constant (TRAIL_HDR) for live and saved trails.
- Home quick panels save prefs only when a value changed.
- Comments brought in line with the code (status bar reserve, settings rows,
  page order, SH1106 frame skip, UiCore header).

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

examples/companion_radio/ui-core/Diagnostics.h

@@ -118,24 +118,6 @@ inline void shortVersion(char* out, size_t n) {
   out[len] = '\0';
 }
 
-// Static system card, one full-width line each. Returns the line count.
-inline int systemLines(Line* lines) {
-  int n = 0;
-  char sv[24];
-  shortVersion(sv, sizeof(sv));
-  addLine(lines, n, "FW %s", sv);
-  addLine(lines, n, "Built %s", FIRMWARE_BUILD_DATE);
-  addLine(lines, n, "Dev %s", board.getManufacturerName());
-  addLine(lines, n, "Node %s", the_mesh.getNodeName());
-  NodePrefs* p = the_mesh.getNodePrefs();
-  if (p) {
-    addLine(lines, n, "Freq %.3f MHz", p->freq);
-    addLine(lines, n, "SF%u BW%.0f CR%u", (unsigned)p->sf, p->bw, (unsigned)p->cr);
-    addLine(lines, n, "TX %d dBm", (int)p->tx_power_dbm);
-  }
-  return n;
-}
-
 // One sample per script the UI font covers, to check coverage by eye. "Acc"
 // takes one letter from each of the keyboard's accent-popup groups.
 inline int fontLines(Line* lines) {

examples/companion_radio/ui-core/NearbyModel.h

@@ -68,16 +68,6 @@ public:
     }
   }
 
-  static const char* typeShort(uint8_t t) {
-    switch (t) {
-      case ADV_TYPE_REPEATER: return "Rpt";
-      case ADV_TYPE_SENSOR:   return "Snsr";
-      case ADV_TYPE_ROOM:     return "Room";
-      case ADV_TYPE_CHAT:     return "Comp";
-      default:                return "?";
-    }
-  }
-
   void bindModel(UiCore* core, NodePrefs* prefs) { _core = core; _prefs = prefs; }
 
   int          count() const          { return _count; }

examples/companion_radio/ui-core/RepeaterControl.h

@@ -61,11 +61,6 @@ static int currentPreset(const NodePrefs* p) {
   return -1;
 }
 
-static const char* currentPresetName(const NodePrefs* p) {
-  const char* name; float f, b; uint8_t s, c;
-  return radioctl::presetAt(p, currentPreset(p), name, f, b, s, c) ? name : "Custom";
-}
-
 static bool choosePreset(NodePrefs* p, int idx) {
   const char* name; float f, b; uint8_t s, c;
   if (!p || !radioctl::presetAt(p, idx, name, f, b, s, c)) return false;

examples/companion_radio/ui-core/RoomSessions.h

@@ -43,7 +43,6 @@ public:
 
   bool loggingIn() const { return _pending; }
   bool loggingIn(const uint8_t* pub_key) const { return _pending && memcmp(_pending_key, pub_key, 4) == 0; }
-  const uint8_t* pendingKey() const { return _pending_key; }
 
   // Local only: the room ACL has no session to tear down (MyMesh::logoutRoom()).
   void logout(const uint8_t* pub_key) {

examples/companion_radio/ui-core/SettingsSchema.h

@@ -249,8 +249,6 @@ static const char* shortLabel(const Setting& s) {
   for (auto& l : SHORT_LABELS) if (l.offset == s.offset) return l.text;
   return s.label;
 }
-// A switch: two values, no labels of its own (on / off, however it's stored).
-static bool isSwitch(const Setting& s) { return !s.option && s.count == 2; }
 // The index of the setting over NodePrefs field `offset`; -1 if none.
 static int indexOf(uint16_t offset) {
   for (int i = 0; i < COUNT; i++) if (ALL[i].offset == offset) return i;

examples/companion_radio/ui-core/UiCore.h

@@ -1,6 +1,7 @@
 #pragma once
 // UI Core: hardware-independent UI state and logic shared by every frontend
-// (ui-new today, ui-lvgl later). See docs/solo/developer/ui-core.md.
+// (ui-new on the OLED / e-ink boards, ui-lvgl on the L2). See
+// docs/solo/developer/ui-core.md.
 //
 // The Core is MyMesh's Listener: it files incoming/outgoing messages into the
 // history, keeps the unread counters, runs the engines, and tells the frontend
@@ -89,7 +90,6 @@ public:
   void    clearAllDMUnread()                      { dm_unread.clearAll(); }
   // Every conversation read: direct, channels, rooms.
   void    markAllRead() { _room_unread = 0; dm_unread.clearAll(); history.clearAllChannelUnread(); }
-  void    reconcileDMUnread()                     { dm_unread.reconcile(history); }
 
   // ── Actions ───────────────────────────────────────────────────────────────
   // Send a DM composed on the device and file it (with end-to-end ACK tracking