feat(agent-development): add cross-references to related skills

[sjnims]

Summary

• Add blockquote after comparison table linking to command-development and skill-development skills
• Add cross-reference after "Choose Commands When" section
• Add cross-reference after "Choose Skills When" section

Problem

Fixes #18

Users reading the agent-development skill's comparison section (agents vs commands vs skills) had no direct links to learn more about developing those other component types.

Solution

Added three cross-references to help users discover related skills:

1. A blockquote after the comparison table: "See also: For command development, load the command-development skill. For skill development, load the skill-development skill."
2. After "Choose Commands When": reference to command-development skill
3. After "Choose Skills When": reference to skill-development skill

Alternatives Considered

• Adding hyperlinks: Not applicable since skills are invoked by name, not URLs
• Adding to a separate "Related Skills" section: Would be less discoverable; inline references are more contextual

Changes

• plugins/plugin-dev/skills/agent-development/SKILL.md: Added 3 cross-references (6 lines)

Testing

• Word count verified: 1,672 words (within 1,500-2,000 ideal range)
• Linting passes: markdownlint shows no issues
• Cross-referenced skills exist and are valid

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🤖 Generated with Claude Code

[claude]

Claude finished @sjnims's task —— View job

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Summary

✅ Looks good - This PR adds helpful cross-references that improve discoverability

What's Good

1. Strategic placement: Cross-references are placed exactly where users would benefit most:

   • After the comparison table (overview reference)
   • After "Choose Commands When" section (contextual reference)
   • After "Choose Skills When" section (contextual reference)

2. Clean implementation: The additions are concise and follow markdown best practices:

   • Blockquote format for the table reference creates nice visual separation
   • Inline references use consistent phrasing
   • Skills are referenced by their invocation names (not URLs)

3. Quality checks pass:

   • ✅ Markdownlint: No issues
   • ✅ Cross-referenced skills exist: Both command-development and skill-development confirmed
   • ✅ Word count (1,672): Well within ideal range (1,500-2,000)

4. Addresses real UX gap: Issue feat(agent-development): add cross-references to related skills #18 correctly identified that users reading the comparison section had no way to discover the related skills without prior knowledge

Checklist Verification

From the PR description:

• ✅ Word count verified: 1,672 words (within range)
• ✅ Linting passes: Confirmed with markdownlint --config .markdownlint.json
• ✅ Cross-referenced skills exist: Both skills confirmed in plugins/plugin-dev/skills/

Suggestions

None - this is a straightforward documentation improvement that enhances the user experience without introducing any issues.

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Recommendation: Approve and merge ✅