fix: resolve reference category spacing and CSS layer priority

[MishtiGarg250]

Hi @Nwakaego-Ego ,thanks for that detailed feedback and for those edge cases, I've gone ahead and pushed updates to address everything.
issue: #1538

• Limit @layer components in global.scss strictly to the h2 bottom margin to prevent Tailwind base styles from overriding other section rules.
• Refactor reference category spacing in ReferenceDirectoryWithFilter:
  • Apply mb-0 unconditionally to category h2 tags.
  • Shift 40px top margin to unnamed subcategory containers to prevent double margins (e.g., Shape) or missing margins (e.g., Typography).
  • Prevent rendering of empty unnamed subcategories.
• Restore package-lock.json to undo accidental deletion.