feat(storybook): add searchable sidebar and deep-link routing support

[geoffjay]

Closes #52

Summary

• Generator enhanced with a Rhai script section containing navigate_to() and on_search_change() for sidebar filtering and component navigation
• All nav buttons have id="nav_{name}" and all pages have id="page_{name}" for script targeting
• launch_storybook() passes --component and --search values via env vars (NEMO_STORYBOOK_COMPONENT, NEMO_STORYBOOK_SEARCH) into the launched app
• Sidebar search input (id="sidebar_search") is wired in the generated XML

Depends on #51. 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
      • feat(storybook): add searchable sidebar and deep-link routing support #74 ◀

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