feat(storybook): add XML config generator crate from component schemas

[geoffjay]

Closes #51

Summary

• New crate crates/nemo-storybook-generator/ with both a library API and a standalone binary
• generate_storybook_xml() creates a complete Nemo XML config by reading ComponentRegistry
• Groups all components by category (Layout, Display, Input, Data, Feedback, Navigation, Charts)
• Each component page includes: title, description, property table, and Preview/XML tab pair
• Property table data is generated from ConfigSchema (name, type, default, required)
• Standalone binary accepts --output <path> flag, defaults to stdout
• Added to workspace Cargo.toml members and dependencies

Part of epic #9.

[geoffjay]

This change is part of the following stack:

• fix(storybook): replace HCL code snippets with XML syntax in styling page #71
  • feat(cli): add nemo storybook subcommand with --component and --search flags #72
    • feat(storybook): add XML config generator crate from component schemas #73 ◀

_{Change managed by git-spice.}