Add transparency modes (glass/blur/reduced) and fix re-enabling Liquid Glass

[Dimillian]

Motivation

• Restore reliable switching between blur and glass by reintroducing the explicit enabled: true when applying Liquid Glass and replacing the binary reduceTransparency flag with a three-value TransparencyMode to express glass, blur, or reduced behaviors.
• Detect runtime glass support and migrate legacy settings so the UI exposes only the appropriate transparency choices and defaults sensibly for new and existing users.

Description

• Reintroduced enabled: true in src/features/app/hooks/useLiquidGlassEffect.ts when applying the glass mode and added logic to disable the effect when the mode is not glass, while updating the hook to accept transparencyMode instead of a boolean.
• Replaced useTransparencyPreference with a richer implementation in src/features/layout/hooks/useTransparencyPreference.ts that persists transparencyMode (migrates from reduceTransparency), checks isGlassSupported, exposes availableModes, and provides setTransparencyMode.
• Wired the new API through the app by updating useAppSettingsController.ts and App.tsx to use transparencyMode, setTransparencyMode, and transparencyModes instead of reduceTransparency.
• Updated SettingsView.tsx, SettingsView.test.tsx, src/styles/settings.css, and src/types.ts to add the segmented radiogroup UI for transparency modes, associated styles, test adjustments, and the TransparencyMode type.

Testing

• No automated tests were executed for this change; existing tests in SettingsView.test.tsx were updated to match the new transparencyMode API but were not run as part of this rollout.

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Codex Task