M0 step 7: Settings, About, Storage, first-boot setup

- lib/apps_model (host-tested): SettingsMenu (rows, readable values,
  choices, validation messages) and SetupWizard (names, Region
  confirmation, timezone; saves only when finished)
- AppManager: modal Apps that Home/Back can't leave (setup wizard)
- SettingsApp: all settings plus Storage (usage, erase SD behind a
  dialog) and About (version, node id, battery, memory, uptime) pages,
  replacing the temporary Diagnostics App
- SetupApp: first-boot wizard, opened modally until SetupDone
- Node id and default names derived from the MAC like Meshtastic
- Widget demo is now hidden (About, then w)
- lib_ldf_mode = deep+ so libraries see each other's headers

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

lib/apps_model/src/settings_menu.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "settings.h"
+
+namespace roro {
+
+// What the Settings App lists: one row per user-facing setting (plus sub-pages), with readable
+// values, choice lists and validation messages. Rendering and navigation live in the App.
+class SettingsMenu {
+   public:
+    enum class Row { LongName, ShortName, Region, Timezone, Brightness, DimTimeout, OffTimeout, Sound, ProbeMacs, Storage, About };
+    enum class Kind { Text, Choice, Toggle, Slider, Page };
+
+    explicit SettingsMenu(Settings& settings) : settings_(settings) {}
+
+    int count() const;
+    Row row(int i) const;
+    Kind kind(int i) const;
+    std::string label(int i) const;
+    std::string value(int i) const;
+
+    // Choice rows
+    std::vector<std::string> choices(int i) const;
+    int currentChoice(int i) const;  // -1 if the current value isn't one of the choices
+    std::string choose(int i, int choice);  // empty on success, otherwise why it was refused
+
+    // Toggle and Slider rows
+    void toggle(int i);
+    void adjust(int i, int direction);
+
+    // Text rows
+    int maxBytes(int i) const;
+    std::string setText(int i, const std::string& text);  // empty on success, otherwise why
+
+   private:
+    Settings& settings_;
+};
+
+}  // namespace roro