Expand Bash library cookbook examples

[codeforester]

Summary

• Add executable cookbook examples for cleanup/temp/version/timeout patterns and arg/list/string composition.
• Link the cookbook examples from the top-level README.
• Wire both cookbook scripts into required-file checks, ShellCheck, and validation execution.

Validation

• shellcheck --severity=error examples/cookbook-cleanup-temp.sh examples/cookbook-args-lists-strings.sh
• examples/cookbook-cleanup-temp.sh >/dev/null
• examples/cookbook-args-lists-strings.sh >/dev/null
• ./tests/validate.sh
• git diff --check

Closes #71