feat: change default wine prefix folder

[PeMeireles]

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This PR solves #2223 by adding a setting to change the default folder Hydra uses for new Wine prefixes.
The new option is available in Settings > Compatibility and lets users choose a different base directory for Hydra-managed Wine prefixes. Hydra still creates one prefix per game, but now uses the configured folder instead of only the built-in default.
To avoid breaking existing installs, changing the default does not move already installed Windows games to the new prefix path. Existing games keep their previous resolved prefix, while the new default only applies to future default-managed prefixes.

[chubbygrannychaser]

LGTM. I reviewed the changed Wine-prefix preference flow and did not find a concrete code-level issue in the current diff.

[sonarqubecloud]

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.5% Duplication on New Code

See analysis details on SonarQube Cloud