feat(keyboard): show digit on each T9 key; complete v1.22 docs

T9 keys now read like a phone keypad — each cell is labelled <digit><group>
(e.g. 2abc), with the digit matching what the multi-tap cycle lands on after
the letters. No separator space: the widest group (".,!?'-") plus the digit
already fills a narrow 128px OLED cell at 3 columns.

Also fills in the v1.22 release notes (T9 keyboard, trail auto-save, Clock
Tools in Tools, Map/Shutdown reorderable, battery-read fix, the UI-audit fix
batch, discover-dedup, favourites self-heal, preset-name placeholder, OLED
frame-skip, e-ink full-refresh) and syncs the solo-feature docs: new Keyboard
settings section, Trail Auto-save row, and Clock Tools reachable from Tools.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/solo_features/settings_screen/settings_screen.md

@@ -94,6 +94,16 @@ The **repeater** mode and its flood filters live on their own screen — see **T
 
 ---
 
+### Keyboard
+
+| Setting  | Options    | Notes                                                                                              |
+| -------- | ---------- | -------------------------------------------------------------------------------------------------- |
+| Layout   | ABC / T9   | On-screen keyboard style. **ABC**: an a-b-c…z grid, one key per letter (the original layout). **T9**: phone-keypad multi-tap — each key is labelled with its **digit** and a letter group (e.g. `2abc`); repeated **Enter** presses cycle through the letters and then the digit itself. |
+
+Applies to every on-screen text field (messages, waypoint labels, room passwords, preset names). Earlier releases labelled the grid *QWERTY*; the layout has always been alphabetical, so it is now named **ABC**.
+
+---
+
 ### Contacts
 
 | Setting  | Options          | Notes                                                |