feat(schema): improve HTML preprocessing for schema generation

Add new preprocess_html_for_schema utility function to better handle HTML cleaning
for schema generation. This replaces the previous optimize_html function in the
GoogleSearchCrawler and includes smarter attribute handling and pattern detection.

Other changes:
- Update default provider to gpt-4o
- Add DEFAULT_PROVIDER_API_KEY constant
- Make LLMConfig creation more flexible with create_llm_config helper
- Add new dependencies: zstandard and msgpack

This change improves schema generation reliability while reducing noise in the
processed HTML.

crawl4ai/types.py

@@ -178,4 +178,10 @@ if TYPE_CHECKING:
         BestFirstCrawlingStrategy as BestFirstCrawlingStrategyType,
         DFSDeepCrawlStrategy as DFSDeepCrawlStrategyType,
         DeepCrawlDecorator as DeepCrawlDecoratorType,
-    )
+    )
+
+
+
+def create_llm_config(*args, **kwargs) -> 'LLMConfigType':
+    from .async_configs import LLMConfig
+    return LLMConfig(*args, **kwargs)