Fix hooks.json schema to use direct format across all plugins

[RyanAlberts]

Fixes #31278

The hooks.json schema validation enforces the direct event format. The previous setup incorrectly nested the events in a {"hooks": {...}} wrapper and included an invalid "description" field, resulting in errors during Claude Code hook execution (e.g., Stop hook error: JSON validation failed). This nested format also triggered jq validation errors inside validate-hook-schema.sh.

Changes Made

• Removed the incorrect {"hooks": {...}} wrapper and "description" field from all hooks.json files across all plugins.
• Added the required "matcher": "*" fields where they were omitted (e.g., hookify, learning-output-style, ralph-wiggum).
• Fixed plugin-dev/skills/hook-development/SKILL.md documentation to instruct developers to use the correct direct format instead of the nested wrapper.
• Verified that all updated hooks.json configurations now cleanly pass validate-hook-schema.sh.

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