docs+ci: pre-merge polish — README, doc accuracy, workflow

README:
- Fix typo "offical" → "official"
- File names in Firmware Variants table now match workflow output
  (solo-<version>-oled.uf2 / solo-<version>-eink.uf2)
- Un-comment the E-ink Display section (now fully supported)
- Clock Screen: "sensor values" → "data fields" (covers Batt%, Nodes, Msgs)
- Tools Screen: mention nearby nodes and auto-advert in the highlight
- Promote Screenshot Tool to its own top-level section (was buried under
  Contributing); fix `uv run tools/screenshot.py` invocation path

Docs:
- favourites_dial: document the 3rd pin-picker tier (all chat contacts
  fallback) added in 0e0e5b93
- clock_screen: Altitude source clarified — onboard sensor (GPS or
  barometric), not always GPS
- message_screen: blank lines around image tables that were inlined

Code:
- UITask.cpp: rename leftover plus_y/plus_label locals to solo_y/solo_label
  in the splash-screen Solo banner

Workflow:
- workflow_dispatch builds previously labelled firmware with the branch
  name (GITHUB_REF_NAME). Resolve BUILD_VERSION to the tag when run on a
  tag push, else dev-<short-sha> so manual runs produce
  solo-dev-abc1234-oled.uf2 etc.

Cleanup:
- remove stray docs/solo_features/settings_screen/set_scr_1_eink copy.png

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docs/solo_features/clock_screen/clock_screen.md

@@ -40,7 +40,7 @@ Up to three data fields are shown below the date separator. Each field displays
 | Humidity    | Hum   | % from onboard sensor                                                     |
 | Pressure    | Pres  | hPa from onboard sensor                                                   |
 | GPS         | GPS   | `lat lon` decimal degrees, or `no fix`                                    |
-| Altitude    | Alt   | metres from GPS                                                           |
+| Altitude    | Alt   | metres from onboard sensor (GPS or barometric)                            |
 | Luminosity  | Lux   | lux from onboard sensor                                                   |
 | CO₂         | CO2   | ppm from onboard sensor                                                   |
 | Contacts    | Nodes | Total contacts in the mesh                                                |