feat: add component comparison section to agent-development skill

[sjnims]

Summary

The agent-development skill explains how to create agents but doesn't help users understand WHEN to use agents versus commands or skills. Adding a comparison section would improve decision-making.

Problem

Users may not know which plugin component is appropriate for their use case:

• Agents - Autonomous, proactive, multi-step tasks
• Commands - User-initiated, explicit invocation
• Skills - Knowledge/guidance, model-invoked contextually

Proposed Addition

Add a new section to SKILL.md:

## When to Use Agents vs Commands vs Skills

| Component | Best For | Triggering | Example Use Case |
|-----------|----------|------------|------------------|
| **Agents** | Autonomous multi-step tasks | Proactive or description-matched | Code review after implementation |
| **Commands** | User-initiated actions | Explicit `/command` invocation | `/deploy production` |
| **Skills** | Knowledge and guidance | Model-invoked based on context | Domain expertise for PDF processing |

### Choose Agents When:
- Task requires autonomous, multi-step execution
- Proactive triggering after certain events is desired
- Specialized subprocess with focused tools needed

### Choose Commands When:
- User should explicitly trigger the action
- Task has clear start/end with specific inputs
- Action should not happen automatically

### Choose Skills When:
- Providing knowledge or procedural guidance
- Extending Claude's domain expertise
- No autonomous execution needed

Benefits

• Helps users choose the right component type
• Reduces misuse of agents where commands/skills would be better
• Provides context for the agent development guidance

Acceptance Criteria

• Clear comparison table added to SKILL.md
• Decision criteria for each component type
• Examples of appropriate use cases

[sjnims]

PR submitted: #15