feat(crawl): implement direct crawl functionality and introduce CacheMode for improved caching control

docs/md_v2/basic/cache-modes.md

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+# Crawl4AI Cache System and Migration Guide
+
+## Overview
+Starting from version X.X.X, Crawl4AI introduces a new caching system that replaces the old boolean flags with a more intuitive `CacheMode` enum. This change simplifies cache control and makes the behavior more predictable.
+
+## Old vs New Approach
+
+### Old Way (Deprecated)
+The old system used multiple boolean flags:
+- `bypass_cache`: Skip cache entirely
+- `disable_cache`: Disable all caching
+- `no_cache_read`: Don't read from cache
+- `no_cache_write`: Don't write to cache
+
+### New Way (Recommended)
+The new system uses a single `CacheMode` enum:
+- `CacheMode.ENABLED`: Normal caching (read/write)
+- `CacheMode.DISABLED`: No caching at all
+- `CacheMode.READ_ONLY`: Only read from cache
+- `CacheMode.WRITE_ONLY`: Only write to cache
+- `CacheMode.BYPASS`: Skip cache for this operation
+
+## Migration Example
+
+### Old Code (Deprecated)
+```python
+import asyncio
+from crawl4ai import AsyncWebCrawler
+
+async def use_proxy():
+    async with AsyncWebCrawler(verbose=True) as crawler:
+        result = await crawler.arun(
+            url="https://www.nbcnews.com/business",
+            bypass_cache=True  # Old way
+        )
+        print(len(result.markdown))
+
+async def main():
+    await use_proxy()
+
+if __name__ == "__main__":
+    asyncio.run(main())
+```
+
+### New Code (Recommended)
+```python
+import asyncio
+from crawl4ai import AsyncWebCrawler, CacheMode  # Import CacheMode
+
+async def use_proxy():
+    async with AsyncWebCrawler(verbose=True) as crawler:
+        result = await crawler.arun(
+            url="https://www.nbcnews.com/business",
+            cache_mode=CacheMode.BYPASS  # New way
+        )
+        print(len(result.markdown))
+
+async def main():
+    await use_proxy()
+
+if __name__ == "__main__":
+    asyncio.run(main())
+```
+
+## Common Migration Patterns
+
+Old Flag | New Mode
+---------|----------
+`bypass_cache=True` | `cache_mode=CacheMode.BYPASS`
+`disable_cache=True` | `cache_mode=CacheMode.DISABLED`
+`no_cache_read=True` | `cache_mode=CacheMode.WRITE_ONLY`
+`no_cache_write=True` | `cache_mode=CacheMode.READ_ONLY`
+
+## Suppressing Deprecation Warnings
+If you need time to migrate, you can temporarily suppress deprecation warnings:
+```python
+# In your config.py
+SHOW_DEPRECATION_WARNINGS = False
+```