docs: stage I3 -- documentation rewritten under docs/solo

Short pages by feature (getting started, messages, contacts, navigation,
tools, settings, lock, hardware) instead of one page per OLED screen, with
Wio Tracker L2 differences as notes; facts checked against the code
(keyboard scripts vs. hold-for-accents, {batt}/{dist}, L2 limits and
settings layout). Developer guides and build flags under docs/solo/developer.
Old docs/solo_features and its ~50 screenshots removed; a hero banner and
three simulator screenshots added; links updated.

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

examples/companion_radio/ui-core/DmUnreadTable.h

@@ -4,7 +4,7 @@
 // and always read back clamped to what the ring still holds for that contact --
 // the same self-healing shape as MessageHistory::chUnread() for channels.
 //
-// Header-only UI Core model (see docs/developer/ui-core.md); no drawing, no
+// Header-only UI Core model (see docs/solo/developer/ui-core.md); no drawing, no
 // screen state.
 
 class DmUnreadTable {

examples/companion_radio/ui-core/SettingsSchema.h

@@ -1,5 +1,5 @@
 #pragma once
-// Declarative settings (docs/developer/ui-core.md, step 4): one table of
+// Declarative settings (docs/solo/developer/ui-core.md, step 4): one table of
 // NodePrefs options with their labels, value lists and side effects, so every
 // frontend renders the same settings without its own per-item code. ui-lvgl
 // draws it as switches and dropdowns, one page per Page below; ui-new still has

examples/companion_radio/ui-core/UiCore.h

@@ -1,6 +1,6 @@
 #pragma once
 // UI Core: hardware-independent UI state and logic shared by every frontend
-// (ui-new today, ui-lvgl later). See docs/developer/ui-core.md.
+// (ui-new today, ui-lvgl later). 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

examples/companion_radio/ui-core/UiCoreHost.h

@@ -4,7 +4,7 @@
 // does, and reports to the frontend through UiEventQueue. This interface is the
 // remainder -- calls that must stay synchronous with mesh processing, or whose
 // logic still lives in the frontend until its extraction step
-// (docs/developer/ui-core.md). None of these may draw or block.
+// (docs/solo/developer/ui-core.md). None of these may draw or block.
 
 class UiCoreHost {
 public:

examples/companion_radio/ui-core/UiEvents.h

@@ -2,7 +2,7 @@
 // Core → frontend events. Engines never call into the frontend (no drawing, no
 // sound, no display power); they push a tagged event here and the frontend
 // drains the queue from its own loop() and reacts in its own way (ui-new:
-// alert overlay + buzzer; ui-lvgl: a dialog). See docs/developer/ui-core.md.
+// alert overlay + buzzer; ui-lvgl: a dialog). See docs/solo/developer/ui-core.md.
 //
 // Fixed-size ring, no heap. When full the oldest event is dropped -- events are
 // hints for the view; the authoritative state stays queryable on the engines.

examples/companion_radio/ui-lvgl/UITask.cpp

@@ -95,7 +95,7 @@ static const char* waypointsFull() {
   return t;
 }
 
-// ui-lvgl skeleton (docs/developer/ui-core.md, step 5): status bar, home,
+// ui-lvgl skeleton (docs/solo/developer/ui-core.md, step 5): status bar, home,
 // conversation list, contact picker, conversation view with compose. Every
 // piece of state it shows comes from the UI Core; this file only draws it.
 

examples/companion_radio/ui-lvgl/UITask.h

@@ -1,7 +1,7 @@
 #pragma once
 // ui-lvgl: the rich (colour + touch) frontend of the UI Core. Wio Tracker L2
 // first. All application state lives in the Core (../ui-core); this class owns
-// only LVGL screens, display power and input. See docs/developer/ui-core.md.
+// only LVGL screens, display power and input. See docs/solo/developer/ui-core.md.
 
 #include <MeshCore.h>
 #include <Arduino.h>