feat(mod-settings-ui): sidebar mod preview panel (icon, version badge, author, description)

[WRXinYue]

Summary

• Add sidebar mod preview panel showing selected mod's icon, title, version badge, author, and description
• Introduce ModSettingsModInfoResolver to resolve mod metadata (name, version, author, description, icon)
• Add localization strings for sidebar preview states (sidebar.modHeader.*, sidebar.modPreview.*)
• Extend ModSettingsUiFactory.Chrome with preview frame and version badge styles
• Add ModSettingsUiMetrics constants for preview sizing
• Integrate preview panel alongside main branch's caching sidebar system (SidebarModCache, pages/sections navigation)

Status: Draft

Still pending:

• Style polish — preview frame sizing, spacing, and color tuning against the updated chrome
• API compatibility — verify ModSettingsModInfoResolver against upstream mod info API changes merged into main
• _focusSelectedModButtonOnNextRefresh / _focusSelectedPageButtonOnNextRefresh focus flow needs end-to-end testing
• Localization keys review (eng/zhs)

Test plan

• Open mod settings with a mod that has icon, version, author, description — verify all fields render
• Open with a mod that has no icon — verify placeholder shows correctly
• Switch between mods — verify preview panel updates
• Navigate pages/sections — verify sidebar selection state and focus are correct
• Keyboard/gamepad navigation through sidebar

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