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

CONTEXT.md

@@ -106,6 +106,10 @@ The regulatory band plan the device transmits under (here EU868). It sets the al
 **Duty Cycle Budget**:
 The share of airtime the Region allows this device to transmit. When it's used up, outgoing traffic waits.
 
+**Help panel**:
+The list of the keys that work on the screen you are on, opened with Fn+h anywhere (or `?` outside Text Entry). Each App answers for its current state; no screen names keys any other way, except the first-start Setup.
+_Avoid_: hints, cheat sheet, shortcuts bar
+
 **Text Entry**:
 When an App is editing text. During Text Entry, `;` `.` `,` `/` type their characters and Fn makes them arrows. Otherwise they are arrows on their own.
 _Avoid_: edit mode, insert mode