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/debug_console_page.cpp

@@ -74,6 +74,13 @@ bool DebugConsolePage::onKey(const KeyEvent& e) {
     return true;
 }
 
+void DebugConsolePage::help(std::vector<KeyHelp>& out) const {
+    if (confirm_) return help::dialog(out);
+    if (typing_) return help::textEntry(out);
+    help::list(out, "switch, or open");
+    out.push_back({", /", "switch the console on or off"});
+}
+
 void DebugConsolePage::draw(Canvas& c) {
     const auto& area = theme::kContent;
     c.setTextDatum(top_left);
@@ -84,8 +91,6 @@ void DebugConsolePage::draw(Canvas& c) {
         widgets::lineEditor(c, editor_, {4, area.y + 22, area.w - 8, 0});
         c.setTextColor(refusal_.empty() ? theme::kMuted : theme::kWarning);
         c.drawString(refusal_.empty() ? "16 to 64 characters. Capitals or not, it's the same." : refusal_.c_str(), 4, area.y + 44);
-        c.setTextColor(theme::kMuted);
-        c.drawString("Enter: save   `: cancel", 4, area.y + 44 + theme::kLineHeight);
         return;
     }