fix no name molecule parsing

[asiomchen]

Fix SDF import for molecules with blank or missing name, fixes #3

Summary

• Molecules whose MOL-block title line is blank were silently dropped or had a corrupted
  molblock stored in frontmatter.

Changes

• src/sdf-parser.ts: Normalize \r\n → \n before splitting; strip the post-delimiter newline only for records at index > 0.
• src/sdf-import.ts: Read the MOL-block title line as the highest-priority name source before falling back to SDF
  properties.
• src/import-utils.ts: Emit |2- instead of | for block scalars whose value starts with \n.
• src/tests/sdf-parser.test.ts / src/tests/import-utils.test.ts: New test suite (Vitest) covering all three
  cases