Fix directory scanning of batch, fish, and PowerShell module scripts

[KingEmma7]

Fix directory scanning of batch, fish, and PowerShell module scripts

What does this PR do?

Fixes #15. Directory scans now include .bat, .cmd, .fish, and .psm1 files through the existing extension filter. Previously these files were silently omitted.

Adds a regression covering all four extensions at the root and in a nested directory, in lowercase and uppercase, with existing supported files and unrelated .bin files as controls. It also checks that the newly collected scripts produce findings. Bumps the patch version to 0.1.4 and documents the fix in the changelog.

Checklist

• Tests pass (node --test)
• Updated docs / README if behavior changed (documented in README.md and CHANGELOG.md)
• Added a CHANGELOG.md entry
• Followed the existing code style

Notes

Prepared with OpenAI Codex assistance, including implementation, regression tests, and this draft.

Validation on macOS (final revision: Node v20.19.5 and v18.18.0):

• Before the source fix: 14 tests passed and the new regression failed, showing all 16 new-extension variants omitted.
• After the fix: all 15 tests passed with node --test on Node 20 and Node 18. The earlier revision also passed npm test on Node 24.
• Clean and malicious fixtures returned exactly 0 and 1 respectively with --fail-on high, for text, JSON, and SARIF output. JSON and SARIF parsed successfully; findings matched clean/flagged expectations.
• All 16 added-extension variants were also checked through the CLI; JSON and SARIF reported exactly the expected paths.
• Package dry run contained the expected eight runtime/documentation files and no test or review artifacts.
• git diff --check passed.

Fixture scripts were read as scanner input, never executed. Node 20 checks ran locally on macOS; GitHub-hosted Linux CI has not run.