chore: release v4.0.0 - sync 550+ skills and restructure docs

skills/bash-defensive-patterns/SKILL.md

@@ -0,0 +1,43 @@
+---
+name: bash-defensive-patterns
+description: Master defensive Bash programming techniques for production-grade scripts. Use when writing robust shell scripts, CI/CD pipelines, or system utilities requiring fault tolerance and safety.
+---
+
+# Bash Defensive Patterns
+
+Comprehensive guidance for writing production-ready Bash scripts using defensive programming techniques, error handling, and safety best practices to prevent common pitfalls and ensure reliability.
+
+## Use this skill when
+
+- Writing production automation scripts
+- Building CI/CD pipeline scripts
+- Creating system administration utilities
+- Developing error-resilient deployment automation
+- Writing scripts that must handle edge cases safely
+- Building maintainable shell script libraries
+- Implementing comprehensive logging and monitoring
+- Creating scripts that must work across different platforms
+
+## Do not use this skill when
+
+- You need a single ad-hoc shell command, not a script
+- The target environment requires strict POSIX sh only
+- The task is unrelated to shell scripting or automation
+
+## Instructions
+
+1. Confirm the target shell, OS, and execution environment.
+2. Enable strict mode and safe defaults from the start.
+3. Validate inputs, quote variables, and handle files safely.
+4. Add logging, error traps, and basic tests.
+
+## Safety
+
+- Avoid destructive commands without confirmation or dry-run flags.
+- Do not run scripts as root unless strictly required.
+
+Refer to `resources/implementation-playbook.md` for detailed patterns, checklists, and templates.
+
+## Resources
+
+- `resources/implementation-playbook.md` for detailed patterns, checklists, and templates.