Fix skill.md detection on Windows (path separator in filter)

[Iammcqwory]

Problem

On Windows, the Capability Signaling (skill-md) check always scores 0/10, even when the project contains a valid skill.md.

walkDir() in src/utils.js builds paths with join() from node:path, which produces backslash-separated paths on Windows (e.g. docs\skill.md). The skill-file filter in src/checkers/skill-md.js then does:

const name = f.split('/').pop().toLowerCase();

Since the path contains no forward slashes on Windows, split('/') returns the whole path as a single element, so name ends up as e.g. docs\skill.md and never equals skill.md / skills.md or starts with skill-. Every skill file is filtered out and the checker reports "No skill.md files found."

Reproduction (Windows)

1. On Windows 11, run npx agentic-seo audit <dir> against any project containing a skill.md (or against this repo's own test fixture test/fixtures/good-site).
2. Capability Signaling reports No skill.md files found. and scores 0/10, while the same command on macOS/Linux finds the file and scores normally.

The existing test skill-md checker > should pass for good-site with skill.md also fails when the suite is run on Windows.

Fix

Split on both separators when extracting the basename:

const name = f.split(/[\\/]/).pop().toLowerCase();

I audited the rest of src/ for the same pattern — this is the only place a filesystem path is split on '/' (other split() usages operate on robots.txt content, CLI flags, and message strings, and relativePath() correctly uses path.relative).

Verification

Full test suite passes on Windows 11 after the fix: 42/42 tests pass, including the previously failing skill-md checker test.

🤖 Generated with Claude Code