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>

examples/companion_radio/ui-new/UITask.cpp

@@ -37,7 +37,7 @@ class SplashScreen : public UIScreen {
   UITask* _task;
   unsigned long dismiss_after;
   char _version_info[12];
-  char _plus_ver[12];
+  char _solo_ver[12];
 
 public:
   SplashScreen(UITask* task) : _task(task) {
@@ -45,13 +45,13 @@ public:
     strncpy(_version_info, MESHCORE_VERSION, sizeof(_version_info) - 1);
     _version_info[sizeof(_version_info) - 1] = '\0';
 
-    // Plus firmware version: strip commit hash suffix (v1.11-abcdef -> v1.11)
+    // Solo firmware version: strip commit hash suffix (v1.15-solo.1-abcdef -> v1.15)
     const char *ver = FIRMWARE_VERSION;
     const char *dash = strchr(ver, '-');
     int plen = dash ? (int)(dash - ver) : (int)strlen(ver);
-    if (plen >= (int)sizeof(_plus_ver)) plen = sizeof(_plus_ver) - 1;
-    memcpy(_plus_ver, ver, plen);
-    _plus_ver[plen] = '\0';
+    if (plen >= (int)sizeof(_solo_ver)) plen = sizeof(_solo_ver) - 1;
+    memcpy(_solo_ver, ver, plen);
+    _solo_ver[plen] = '\0';
 
     dismiss_after = millis() + BOOT_SCREEN_MILLIS;
   }
@@ -79,15 +79,15 @@ public:
     display.drawTextCentered(display.width()/2, date_y, FIRMWARE_BUILD_DATE);
 
 #ifdef FIRMWARE_SOLO_BUILD
-    int plus_y = date_y + step;
-    display.fillRect(0, plus_y - 1, display.width(), lh + 2);
+    int solo_y = date_y + step;
+    display.fillRect(0, solo_y - 1, display.width(), lh + 2);
     display.setColor(DisplayDriver::DARK);
-    char plus_label[24];
-    if (_plus_ver[0])
-      snprintf(plus_label, sizeof(plus_label), "Plus %s for Wio", _plus_ver);
+    char solo_label[24];
+    if (_solo_ver[0])
+      snprintf(solo_label, sizeof(solo_label), "Solo %s for Wio", _solo_ver);
     else
-      snprintf(plus_label, sizeof(plus_label), "Plus for Wio");
-    display.drawTextCentered(display.width()/2, plus_y, plus_label);
+      snprintf(solo_label, sizeof(solo_label), "Solo for Wio");
+    display.drawTextCentered(display.width()/2, solo_y, solo_label);
     display.setColor(DisplayDriver::LIGHT);
 #endif