One firmware: the Debug Console in every build, off until switched on, with the device's own token

There is no Debug Build any more (ADR 0010, issue #68, Q188 to Q195). The
console and the test commands are compiled into every firmware. It listens
only while Settings > Debug Console is on, which isn't the default; off,
neither its task nor its 4 KB ring exists. The token is made by the device
and shown on that page; a client proves it knows it by answering a challenge
with an HMAC, so it never crosses the network, and five wrong answers close
the console for a minute. DBG in the Status Bar while it listens.

Over USB serial only: debug on, debug token <value>, debug token new.
scripts/flash.sh --debug uses them to set a device up with the developer's
token. scripts/rdbg.py takes the token from -t, $RORO_DEBUG_TOKEN or the
file, answers the challenge, and fetches a release's ELF to decode a crash.

Gone: the cardputer-adv-debug environment, RORO_DEBUG, the +debug version,
scripts/debug_flags.py, update install ... force, and the rule that a Debug
Build doesn't install releases. Old clients and old firmwares don't talk to
each other.

Against the builds it replaces: 30 KB more flash and 88 bytes more static
RAM than the release, 4 KB less RAM than the Debug Build. 468 host tests.
Checked on the device: off by default, login, the pause after wrong tokens,
Safe Mode with the console, the setting surviving an update, debug off.

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

lib/apps_model/src/settings_menu.cpp

@@ -24,7 +24,7 @@ const RowDef kRows[] = {
     {Row::Coordinates, Kind::Toggle, "Coordinates"},
     {Row::ProbeMacs, Kind::Toggle, "Probe MACs"}, {Row::Wifi, Kind::Page, "Wi-Fi"},
     {Row::CheckUpdates, Kind::Toggle, "Check for updates"}, {Row::Firmware, Kind::Page, "Firmware"},
-    {Row::About, Kind::Page, "About"},
+    {Row::DebugConsole, Kind::Page, "Debug Console"}, {Row::About, Kind::Page, "About"},
 };
 
 const int kDimSeconds[] = {10, 15, 30, 60, 120, 300};
@@ -86,6 +86,7 @@ std::string SettingsMenu::value(int i) const {
         case Row::Coordinates: return settings_.getBool(Setting::CoordinatesDms) ? "Deg min sec" : "Decimal";
         case Row::ProbeMacs: return settings_.getBool(Setting::ProbeMacRaw) ? "Raw" : "Pseudonymised";
         case Row::Wifi: return settings_.getBool(Setting::WifiEnabled) ? "On" : "Off";
+        case Row::DebugConsole: return settings_.getBool(Setting::DebugConsole) ? "On" : "Off";
         default: return "";
     }
 }

lib/apps_model/src/settings_menu.h

@@ -11,7 +11,7 @@ namespace roro {
 // 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, Gnss, GnssQuiet, Coordinates, ProbeMacs, Wifi, CheckUpdates, Firmware, About };
+    enum class Row { LongName, ShortName, Region, Timezone, Brightness, DimTimeout, OffTimeout, Sound, Gnss, GnssQuiet, Coordinates, ProbeMacs, Wifi, CheckUpdates, Firmware, DebugConsole, About };
     enum class Kind { Text, Choice, Toggle, Slider, Page };
 
     explicit SettingsMenu(Settings& settings) : settings_(settings) {}