feat: initialize marketing skills repository with content-creator skill

Add comprehensive content-creator skill package including:
- Brand voice analyzer (Python CLI tool)
- SEO optimizer with scoring and recommendations
- Brand guidelines with 5 personality archetypes
- 15+ content frameworks and templates
- Platform-specific social media optimization guides
- Content calendar template
- Marketing skills roadmap for future expansion

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,16 @@
+.vscode
+.DS_Store
+AGENTS.md
+PROMPTS.md
+.env
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+.env.development
+.env.test
+.env.production
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local