fix(web): add post-generation verification step and harden generated spec handling

[21pounder]

Summary

This PR fixes generation reliability issues reported in #129 and adds a quick verification + feedback step in the
playground after generation.

Problems

• Generated Rating could become read-only in feedback/form scenarios.
• Generated Select/Radio options could render as [object Object].
• No quick post-generation verification/feedback loop for users.

Changes

• Made Rating interactive in playground registry (state binding + on.change support).
• Added option normalization for Select/Radio to handle object-shaped options safely.
• Added spec verification module (structural + semantic checks).
• Added verification panel in playground with actions:
  • Looks good
  • Fix issues (regenerate with issue-aware repair prompt)
  • Regenerate
• Tightened generation prompt rules for interactive rating and select/radio option shape.
• Updated README with verification capability note.

Validation

• Ran pnpm type-check successfully.

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