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.

changelog/1.7.4.html

@@ -76,7 +76,7 @@
                         <a href="https://t.me/nebulaauth">t.me/nebulaauth</a>
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-              <li><b>FIX:</b> Resolved issue where a "Confirmation Error" notification appeared despite the confirmation being successful.</li>
+                <li><b>FIX:</b> Resolved issue where a "Confirmation Error" notification appeared despite the confirmation being successful.</li>
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