Refresh shadcn auth component comments

[phuctm97]

Summary

• Keep generated shadcn comments in refreshed world sidebar and auth router components
• Adapt generated Better Auth UI auth comments to the existing AuthRouter naming
• Update the shadcn-ui skill to keep generated comments and require one test file per generated source file

Validation

• bun --bun biome check
• bun --bun tsc --build
• bun run --cwd packages/world build
• bun run --cwd packages/world test --coverage --reporter=verbose --maxWorkers=1