docs: add prerequisites section for utility script dependencies

[sjnims]

Description

Add documentation for utility script dependencies (jq, grep, sed) so users know what tools are required before running validation scripts.

Type of Change

• Documentation update (improvements to README, CLAUDE.md, or component docs)

Component(s) Affected

• Skills (methodology and best practices)
• Documentation (README.md, CLAUDE.md, SECURITY.md)

Motivation and Context

Users may encounter confusing errors if external tools like jq are missing. This documents the requirements upfront.

Fixes #152

Solution

• README.md: Added "For Utility Scripts" subsection to Prerequisites with tool/version table, environment check commands, and installation note
• hook-development/SKILL.md: Added prerequisites blockquote referencing the main README

Note on Bash Version

The issue originally suggested bash 4.0+ but I verified the scripts only use [[ =~ ]] regex matching which is available in bash 3.2+ (macOS default). Updated accordingly.

Changes

• README.md: Added utility script prerequisites section
• plugins/plugin-dev/skills/hook-development/SKILL.md: Added prerequisites note

Testing

• Linting passes (markdownlint)
• Verified bash version requirement by grepping for 4.0+ features (none found)

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🤖 Generated with Claude Code

[claude]

Claude finished @sjnims's task in 55s —— View job

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PR Review Complete ✅

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Summary

Looks good! This PR effectively addresses issue #152 by documenting utility script dependencies upfront, preventing confusing errors for users.

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What's Good

1. Clear Prerequisites Table: The table format in README.md makes it easy to see required tools, versions, and purposes at a glance.

2. Practical Environment Check: Including commands to verify installations (bash --version | head -1, jq --version, etc.) helps users quickly validate their setup.

3. Accurate Bash Version: Good catch on bash 3.2+ vs 4.0+. The author verified the scripts only use features available in bash 3.2+ (macOS default), which improves compatibility.

4. Cross-References: The hook-development SKILL.md appropriately references the main README for setup details, maintaining a single source of truth.

5. Helpful Installation Note: The note about jq needing installation with platform-specific commands (brew install jq, apt install jq) is user-friendly.

6. Markdown Quality: All markdown linting passes with no issues.

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Checklist Verification

• ✅ Documentation Quality: Clear, well-organized prerequisites section
• ✅ Markdown Linting: Passes markdownlint with .markdownlint.json rules
• ✅ Cross-References: Proper linking between SKILL.md and README.md
• ✅ Accuracy: Bash version correctly identified as 3.2+ (not 4.0+)
• ✅ User Experience: Provides actionable verification commands and installation guidance
• ✅ No Component Changes: Only documentation updated (no plugin components affected)

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Technical Details

Files Changed:

• README.md: Added "For Utility Scripts" subsection with tool requirements table
• plugins/plugin-dev/skills/hook-development/SKILL.md: Added prerequisites blockquote referencing main README

Markdown Linting: ✅ No issues found

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This PR is ready to merge. It provides clear, accurate documentation that will help users avoid confusing errors when running utility scripts.