[BUG] SKILL.md with a UTF-8 BOM fails frontmatter parse

Description

parse_frontmatter requires SKILL.md to start with ---. Files saved with a UTF-8 BOM start with \ufeff---, so valid skills raise SkillParseError. Editors on Windows commonly write a BOM.

Steps to Reproduce

from pathlib import Path
from crewai.skills.parser import parse_skill_md

path = Path("SKILL.md")
path.write_bytes(b"\xef\xbb\xbf---\nname: my-skill\ndescription: d\n---\nBody")
parse_skill_md(path)

Expected behavior

A leading UTF-8 BOM is ignored. The skill parses.

Screenshots/Code snippets

SkillParseError: SKILL.md must start with '---' frontmatter delimiter

Operating System

Windows 11

Python Version

3.12

crewAI Version

main