creator feedback batch: 9 fixes from initial review

1. About box bg → #0A0C1A (matches icon bg)
2. Elements panel collapses when no element selected / scene changes
3. OpacityChip moved from preview overlay into Elements panel
4. Color picker fix: cast to SceneElement not Source (WebcamSceneConfig was silently blocked)
5. Red left accent bar on selected items in Scene/Source lists
6. ✓ character replaced with Path checkmark icon in Elements panel
7. Removed ToolTip='Applied' from green check buttons
8. Created bugs.md with first entry (iTunes audio on mic meter)
9. Full logo in README + About box uses ytLlive-logo.png

README.md

@@ -1,5 +1,9 @@
 # ytLlive
 
+<p align="center">
+  <img src="Assets/ytLlive-logo.png" alt="ytLlive — livestream smarter" height="120"/>
+</p>
+
 A creator-proof live-streaming and recording app for YouTube — native Windows (C# / WPF / .NET 8).
 
 ## Screenshot