Refine UX, fix auth crash, and revert to .NET 8.0

- Reverted target framework to .NET 8.0 for stability.
- Added autofocus to all dialog input fields (e.g. password dialogs).
- Fixed crash when relogging into accounts without Steam Guard and added proper error message.
- Unified and improved “Confirm Action” dialog design and text clarity.
- Added setting to disable ripple effect animations for better performance.
- Reduced minimum auto-confirmation timer interval from 10s to 5s.
- App now auto-selects the most appropriate language on first launch.
- Added trimming to proxy parse input
- Fixed incorrect hint about maFile binding when using login-based mode.
- Added ESC key behavior to remove focus from account search
- Minor UI polish and cleanup across dialogs.

.gitignore

@@ -360,4 +360,6 @@ MigrationBackup/
 .ionide/
 
 # Fody - auto-generated XML schema
-FodyWeavers.xsd
+FodyWeavers.xsd
+
+todo/