chore: Remove maintenance files for cleaner plugin distribution

Remove internal development files that aren't needed by plugin users:
- CLAUDE.md (personal development guidelines)
- ENHANCEMENT_PLAN.md (internal planning)
- ENHANCEMENTS_SUMMARY.md (internal notes)
- SKILLS_USAGE_GUIDE.md (redundant with README.md)
- skills/MIGRATION_GUIDE.md (internal migration notes)
- skills/REFACTORING_SUMMARY.md (internal refactoring notes)
- skills/_INDEX.md.archive (old backup)

Update .gitignore to exclude:
- .claude/ (personal workspace)
- Maintenance files (CLAUDE.md, ENHANCEMENT*.md, etc.)
- Skills archive and internal docs

This keeps the plugin repository focused on what end users need:
- Skills library (292 skills)
- Commands (/skills)
- Documentation (README.md, PLUGIN.md, MIGRATION.md)
- Plugin manifest (.claude-plugin/plugin.json)
- License (MIT)

Author: rand

.gitignore

@@ -110,6 +110,19 @@ coverage/
 # Beads task management
 .beads/
 
+# Claude Code workspace (personal)
+.claude/
+
+# Maintenance files (not for plugin distribution)
+CLAUDE.md
+ENHANCEMENT*.md
+*ENHANCEMENT*.md
+SKILLS_USAGE_GUIDE.md
+skills/_INDEX.md.archive
+skills/MIGRATION_GUIDE.md
+skills/REFACTORING_SUMMARY.md
+skills/_archive/
+
 # OS
 Thumbs.db
 Desktop.ini