feat(aidd-ui): aidd-ui runs as one ordered recipe, each section reviewed before the next

[blafourcade]

A user generating a UI should follow one top-to-bottom recipe, not pick skills from a menu and guess the order.

Scope

• Draw the full structure of aidd-ui as a recipe: each skill is a section, its sub-actions run in order.
• The product-critic agent gates each section before the next opens.
• Sections chain through requires / next / produces.
• Structure only: every action is a stub. The logic lands in follow-up PRs.
• Replaces the alpha smoke-test skill 01-hello.

Acceptance criteria

• Sections declare their chaining explicitly.
• A section cannot open before the critic has passed the previous one.
• No action carries logic yet, and that is stated in the skill.

Implemented in PR #330 (draft).