docs(skill): invoke PowerShell wrapper with call operator - #26

Summary

Prefix the documented Windows PowerShell wrapper path with the call operator (&) so PowerShell executes the script instead of parsing the path as a string literal.

Reproduction

Applied the skill to harnessclaw/harnessclaw-engine, the Go repository in the iflytek-astron topic (go 1.26.1):

• documented command without &: PowerShell exits with ParserError / UnexpectedToken at the list argument;
• corrected command with &: wrapper exits 0, installs/executes v0.1.1, detects the target file's Go version, and returns the applicable guideline list.

Validation

• go test ./internal/cli ./internal/goversion ./internal/guidelines ./internal/guidelines/schema — pass
• go test ./... — all packages pass except the existing CRLF-sensitive TestFeaturesMarkdownInSync on this Windows checkout; this PR does not modify FEATURES.md, the generator, or guideline data
• git diff --check — pass

Closes #25.