second-brain 0.1.0

• Initial release of the "second-brain" skill, a structured personal knowledge base powered by Ensue.
• Supports capturing and retrieving knowledge via intuitive commands (e.g., "save this", "what do I know about").
• Clearly defined namespace for organizing concepts, toolbox, patterns, references, notes, and journal entries.
• Provides strict guidelines for high-quality, retrievable content—ensuring future usefulness and security.
• Includes ready-to-use templates for various content types (concepts, tools, patterns, references).
• Implements robust interaction policies: always confirm before saving, avoid storing secrets, and enforce quality standards.