questionnaire: Add a Questionnaire component

[suxiaoshao]

Summary

• Add a composable Questionnaire state model and styled parts for single and multiple choice, freeform answers, skip, validation, shortcuts, focus, progress, navigation, and submission.
• Reuse Radio, Checkbox, Input, Button, Kbd, semantic theme tokens, and Size throughout the presentation layer.
• Add localized strings, comprehensive Story coverage, and synchronized English and Chinese documentation.

Validation

• cargo test -p gpui-component questionnaire --lib (15 passed)
• cargo clippy -p gpui-component --lib --tests -- --deny warnings
• Native and nightly WASM Story checks
• VitePress build and git diff --check

Visual acceptance was intentionally not performed. This implementation was created with AI assistance and reviewed through targeted tests.

Fixes #2860

[madcodelife]

Thanks.