Refine Settings hierarchy and visual design

[DeadWaveWave]

Summary

• redesign the Settings shell and navigation for clearer page-level information architecture
• introduce a shared Page → Group → Module → Row hierarchy across all settings pages
• simplify Worker, task tags, workspace, integrations, diagnostics, and other dense sections
• preserve settings ownership, persistence, search anchors, keyboard behavior, and accessibility semantics
• document the Settings grouping rules and add focused visual and hierarchy coverage

UX principles

• one restrained shared surface per settings group
• nested modules use typography and spacing instead of additional cards
• entity collections retain compact cards or chips only where identity and actions require them
• consistent light, dark, narrow-window, English, and Chinese behavior

Verification

• pnpm pre-commit
• 89 related test files / 279 tests passed
• 244 Electron E2E tests passed, 47 platform or environment skips, 0 failures
• lint, typecheck, formatting, naming, line-length, secret checks, and production build passed