fix(security): validate FEATURE arg in check-status.sh to prevent path traversal

[xiaolai]

Automated audit: This PR was generated by NLPM, a natural language programming linter, running via claude-code-action. Please evaluate the diff on its merits.

Bug

In skills/dev-lifecycle/scripts/check-status.sh, the FEATURE argument (line 12) is interpolated directly into file paths like feature-${FEATURE}.md without any input validation. A maliciously crafted feature name such as ../../etc/passwd or ../secrets/config would cause the script to access unintended files outside the docs/ai/ directory.

While the script only performs read operations ([[ -f ... ]] and grep), path traversal can still leak information about the existence and content of files outside the intended scope.

Fix

Added a one-line guard immediately after reading FEATURE="$1" that rejects any feature name not matching ^[a-zA-Z0-9_-]+$:

if [[ ! "$FEATURE" =~ ^[a-zA-Z0-9_-]+$ ]]; then
  echo "Error: feature name must contain only letters, digits, hyphens, and underscores"
  exit 1
fi

This allows all valid feature names (letters, digits, hyphens, underscores) while blocking path traversal sequences. The error message tells users what format is expected.

Impact

Low severity. No code execution risk — purely a file-read path traversal guard. The fix is minimal and backwards-compatible with all valid feature name formats.