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/apps/setup_app.cpp

@@ -44,6 +44,24 @@ bool SetupApp::onKey(const KeyEvent& e) {
     return true;
 }
 
+void SetupApp::help(std::vector<KeyHelp>& out) const {
+    switch (wizard_.step()) {
+        case Step::LongName:
+        case Step::ShortName: help::textEntry(out, "next step"); break;
+        case Step::Region:
+        case Step::Timezone:
+            help::list(out, "choose it, next step");
+            out.push_back({"`", "the step before"});
+            break;
+        default:
+            out.push_back({"Enter", "continue"});
+            out.push_back({"`", "the step before"});
+            break;
+    }
+}
+
+// The one place that names keys on the screen (Q200): someone in their first minute doesn't know
+// the help key yet, and this is where they learn it.
 void SetupApp::draw(Canvas& c) {
     const auto& area = theme::kContent;
     auto heading = [&](const char* text) {
@@ -63,6 +81,7 @@ void SetupApp::draw(Canvas& c) {
             heading("Welcome to roro9stack");
             note("Let's set up this device: your names on the mesh, your radio region and your timezone.",
                  area.y + 22, theme::kText);
+            note("One key to know: Fn + h lists the keys of the screen you're on.", area.y + 22 + 4 * theme::kLineHeight, theme::kAccent);
             note("Enter: continue", area.y + area.h - 14);
             break;
         case Step::LongName:
@@ -88,8 +107,10 @@ void SetupApp::draw(Canvas& c) {
                           [this](int i) { return wizard_.choiceLabel(i); });
             break;
         case Step::Done:
-            heading("All set");
-            note("You can change all of this later in Settings.", area.y + 22, theme::kText);
+            heading("All set. One key to remember:");
+            note("Fn + h, on any screen, lists the keys that work there. No screen names its keys: that key does. Try it now.",
+                 area.y + 22, theme::kAccent);
+            note("The rest can be changed later in Settings.", area.y + 22 + 4 * theme::kLineHeight, theme::kText);
             note("Enter: start   `: go back", area.y + area.h - 14);
             break;
     }