Help: Fn+h lists the keys of the screen you're on, and no screen names its keys any more (#69)

Fn+h on any screen, text fields included, and ? outside Text Entry, open a
panel over the content area: the screen's own keys, then the ones that work
everywhere. Every App declares its keys for the state it is in (pages,
viewers, dialogs and text fields answer for themselves); the App manager
opens the panel and takes every key while it is open.

About 30 hint lines are gone, from every App. What stays on a screen is
state. The first-start Setup keeps its hints and teaches the key; a device
set up before gets one Toast, once. The guide and the FAQ open with it.
`key help` over the consoles.

476 host tests (8 new). Checked on the device with key help and screenshots:
the Launcher, all nine Apps and several of their states. 8.5 KB of flash and
40 bytes of static RAM. Decisions Q196 to Q203 in docs/milestones/U1.md.

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

src/main.cpp

@@ -225,6 +225,13 @@ void setup() {
     services.startAll(millis());
     apps->begin();
     if (!settings.getBool(Setting::SetupDone)) apps->openModal("setup");
+    // No screen names its keys any more (issue #69): Setup teaches the help key to a new device, and
+    // one that was set up before this firmware is told once, here.
+    if (!settings.getBool(Setting::HelpTold)) {
+        if (settings.getBool(Setting::SetupDone))
+            bus.publish(Event::withText(EventType::Notification, "Fn+h: the keys of any screen", static_cast<int32_t>(NotificationLevel::Info)));
+        settings.setBool(Setting::HelpTold, true);
+    }
     console.printf("%s %s ready, free heap %u, last start: %s\n", kProductName, versionString(), ESP.getFreeHeap(),
                    system_info::resetReason());
     if (system_info::resetWasCrash()) {
@@ -555,7 +562,7 @@ static const char* const kHelp =
     "gnss status | gnss restart | gnss track start|stop | gnss nmea on|off | gnss send <sentence without $ and checksum>\n"
     "crash             the last crash: firmware, reason, task, backtrace\n"
     "coredump erase    forget the core dump in flash\n"
-    "key <name|char>   press a key: up down left right select back home del tab space, or one character\n"
+    "key <name|char>   press a key: up down left right select back home del tab space help, or one character\n"
     "wifi status | wifi add <ssid><TAB><password>\n"
     "wifi ip <ssid> dhcp | wifi ip <ssid> <address>/<prefix> [gateway]   a Saved Network's IP setting\n"
     "wifi dns <a> [b] | wifi dns always on|off | wifi ntp <a> [b]   DNS and NTP servers\n"
@@ -842,7 +849,7 @@ static void runCommand(String line, bool fromSerial = false) {
         String k = line.substring(4);
         Key key = k == "up" ? Key::Up : k == "down" ? Key::Down : k == "left" ? Key::Left
                 : k == "right" ? Key::Right : k == "back" ? Key::Back : k == "home" ? Key::Home
-                : k == "del" ? Key::Delete : k == "tab" ? Key::Tab : Key::Select;
+                : k == "del" ? Key::Delete : k == "tab" ? Key::Tab : k == "help" ? Key::Help : Key::Select;
         KeyEvent ev = k == "space"                       ? KeyEvent::character(' ')
                       : k.length() == 1 && k[0] > ' ' ? KeyEvent::character((unsigned char)k[0])
                                                       : KeyEvent::of(key);