feat(cli): add command line interface with comprehensive features

Implements a full-featured CLI for Crawl4AI with the following capabilities:
- Basic and advanced web crawling
- Configuration management via YAML/JSON files
- Multiple extraction strategies (CSS, XPath, LLM)
- Content filtering and optimization
- Interactive Q&A capabilities
- Various output formats
- Comprehensive documentation and examples

Also includes:
- Home directory setup for configuration and cache
- Environment variable support for API tokens
- Test suite for CLI functionality

docs/examples/cli/llm_schema.json

@@ -0,0 +1,26 @@
+{
+  "title": "NewsArticle",
+  "type": "object",
+  "properties": {
+    "title": {
+      "type": "string",
+      "description": "The title/headline of the news article"
+    },
+    "link": {
+      "type": "string",
+      "description": "The URL or link to the full article"
+    },
+    "details": {
+      "type": "string", 
+      "description": "Brief summary or details about the article content"
+    },
+    "topics": {
+      "type": "array",
+      "items": {
+        "type": "string"
+      },
+      "description": "List of topics or categories associated with the article"
+    }
+  },
+  "required": ["title", "details"]
+}