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

src/platform/identity.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <Arduino.h>
+
+#include <cstdio>
+#include <string>
+
+namespace roro::identity {
+
+// Node number as Meshtastic derives it: the last four bytes of the chip's MAC address.
+inline uint32_t nodeNum() {
+    uint64_t mac = ESP.getEfuseMac();  // byte 0 of the MAC is the lowest byte
+    auto byte = [mac](int i) { return static_cast<uint32_t>((mac >> (8 * i)) & 0xFF); };
+    return (byte(2) << 24) | (byte(3) << 16) | (byte(4) << 8) | byte(5);
+}
+
+// "!2f762fa4"
+inline std::string nodeId() {
+    char buf[12];
+    std::snprintf(buf, sizeof(buf), "!%08lx", static_cast<unsigned long>(nodeNum()));
+    return buf;
+}
+
+// Suggested names for the setup wizard: "roro9stack 2fa4" and "2fa4".
+inline std::string defaultShortName() {
+    char buf[8];
+    std::snprintf(buf, sizeof(buf), "%04lx", static_cast<unsigned long>(nodeNum() & 0xFFFF));
+    return buf;
+}
+inline std::string defaultLongName() { return "roro9stack " + defaultShortName(); }
+
+}  // namespace roro::identity