Fix Malformed Preset Filenames

[unreference]

This fixes #6586.

Preset names are used directly as filenames without sanitization. Characters like : are illegal in Windows filenames -- on NTFS, : creates an Alternate Data Stream instead of a regular file. A preset called "test :)" bricks the app. The save produces a malformed file, LoadPresets calls nlohmann::json::parse on it with no error handling, and the resulting exception crashes the app on every subsequent launch.

• New SanitizeFilename function replaces < > : " / \ | ? * and control characters with _, stripping trailing dots and spaces. Applied in both SavePreset and FormatPresetPath (used by delete). The preset's display name in JSON is unchanged -- the user still sees their original name in the UI.
• std::ofstream doesn't throw on failure -- it fails silently. An is_open() check after opening lets the app log an error and returns instead of writing to a failed stream.
• Wrapped nlohmann::json::parse in a try-catch so a malformed preset file logs an error and is skipped instead of crashing the app. This also serves to recover any existing installations stuck in a crash loop from previously created bad presets.