Scaffold AI-powered test automation plugin

[NehemyaM]

Motivation

• Provide an AI-driven plugin scaffold to replace repetitive manual testing with automated, agent-guided test planning and execution.
• Offer a minimal, editable integration point (skill + hook + script) so teams can wire their own test commands and CI triggers.

Description

• Added a new plugin at plugins/ai-test-automation with a placeholder manifest at plugins/ai-test-automation/.codex-plugin/plugin.json containing full schema placeholders for later customization.
• Added a user-facing plugins/ai-test-automation/README.md describing workflows and example prompts for generating and running tests.
• Added an AI skill template at plugins/ai-test-automation/skills/testing-agent/SKILL.md that defines goals, procedure, and output format for a QA automation agent.
• Added hook configuration plugins/ai-test-automation/hooks.json and an executable placeholder script plugins/ai-test-automation/scripts/run_test_scan.sh wired to a post-change-test-scan event.
• Registered the plugin in the local marketplace at .agents/plugins/marketplace.json so it is discoverable as a local plugin entry.

Testing

• Ran a shell syntax check on the script with bash -n plugins/ai-test-automation/scripts/run_test_scan.sh which succeeded.
• Validated JSON files with python3 -m json.tool on plugins/ai-test-automation/hooks.json, plugins/ai-test-automation/.codex-plugin/plugin.json, and .agents/plugins/marketplace.json, all of which parsed successfully.

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Codex Task