feat(ui): semibold window title + "Lite" suffix on the lite build

- Draw the brand word "ObsidianDragon" in Ubuntu Medium (the closest weight the
  project ships — no true 600 face) as a stand-in for semibold; append "Lite" in the
  Regular font under DRAGONX_LITE_BUILD so the lite window reads "ObsidianDragonLite".
- Fix a misleading comment: pool mining (and thus auto-balance) is available in both
  builds; only solo mining is full-node-only.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app.cpp

@@ -134,7 +134,7 @@ long long steadyNowMs()
 void App::updatePoolAutoBalance()
 {
     if (!settings_) return;
-    if (!supportsPoolMining()) return;  // pool mining is full-node only
+    if (!supportsPoolMining()) return;  // pool mining is available in both builds (solo is full-node only)
     if (settings_->getPoolSelectMode() != config::Settings::PoolSelectMode::AutoBalance) return;
     if (!settings_->getPoolMode()) return;  // only while POOL mode is selected
 
@@ -1478,9 +1478,18 @@ void App::render()
             // Apply header text opacity
             int a = (int)((float)((textCol >> 24) & 0xFF) * hdrOpacity);
             textCol = (textCol & 0x00FFFFFF) | ((ImU32)a << 24);
-            dl->AddText(titleFont, titleFontSize,
-                        ImVec2(logoX, textY),
-                        textCol, "ObsidianDragon");
+
+            // Base brand word in a heavier (Ubuntu Medium) weight as the "semibold" —
+            // the project ships no true 600 face. On the lite build the "Lite" suffix is
+            // appended in the Regular title font.
+            ImFont* baseFont = ui::material::Type().subtitle2();  // Ubuntu Medium
+            if (!baseFont) baseFont = titleFont;
+            const char* baseWord = "ObsidianDragon";
+            dl->AddText(baseFont, titleFontSize, ImVec2(logoX, textY), textCol, baseWord);
+#if DRAGONX_LITE_BUILD
+            float baseW = baseFont->CalcTextSizeA(titleFontSize, FLT_MAX, 0.0f, baseWord).x;
+            dl->AddText(titleFont, titleFontSize, ImVec2(logoX + baseW, textY), textCol, "Lite");
+#endif
         }
     }