feat: add support for list meta property (start and counterType)

[Maverick341]

Description

Adds support for the meta property in Editor.js list blocks, which includes start (custom starting number) and counterType (numeric, roman, alpha) properties.

Changes

• Added meta?: { start?: number; counterType?: ... } to ListBlockData interface
• Added start and counterType props to Group component
• Implemented start attribute for ordered lists
• Implemented counterType inline styling using listStyleType
• Fully backward compatible

Testing

• All existing tests pass ✓
• Added comprehensive tests covering:
  • Custom start values (1, 2, 3, 5, etc.)
  • All counter types (numeric, lower-roman, upper-roman, lower-alpha, upper-alpha)
  • Combined start + counterType
  • Nested lists with inherited meta properties
  • Backward compatibility (lists without meta)

Related

Addresses Editor.js now providing meta property in list blocks.