feat(web-ui): refactor SkillsScene with tab layout, sidebar nav, and enhanced filters

[GCWing]

Summary

• Replace two-column split layout (market / installed) with tab-based Installed + Discover layout
• Add sidebar navigation with filter categories: All, Built-in, User, Project, Suite
• Redesign SkillCard from fixed-size to responsive grid-based card
• Extend useInstalledSkills filter logic to separate built-in and suite categories
• Add i18n entries for new filters, categories, and details button (en-US + zh-CN)
• Localize session type labels in zh-CN common.json

Test Plan

• Type-check and lint pass
• Skills scene renders correctly with new tab layout
• Sidebar filters work for All, Built-in, User, Project, Suite
• SkillCard displays correctly in grid layout
• i18n translations render correctly in both en-US and zh-CN
• Pagination works in both Installed and Discover tabs