Refactor adaptive crawling state management

- Renamed `CrawlState` to `AdaptiveCrawlResult` to better reflect its purpose.
- Updated all references to `CrawlState` in the codebase, including method signatures and documentation.
- Modified the `AdaptiveCrawler` class to initialize and manage the new `AdaptiveCrawlResult` state.
- Adjusted example strategies and documentation to align with the new state class.
- Ensured all tests are updated to use `AdaptiveCrawlResult` instead of `CrawlState`.

docs/md_v2/api/digest.md

@@ -9,7 +9,7 @@ async def digest(
     start_url: str,
     query: str,
     resume_from: Optional[Union[str, Path]] = None
-) -> CrawlState
+) -> AdaptiveCrawlResult
 ```
 
 ## Parameters
@@ -31,7 +31,7 @@ async def digest(
 
 ## Return Value
 
-Returns a `CrawlState` object containing:
+Returns a `AdaptiveCrawlResult` object containing:
 
 - **crawled_urls** (`Set[str]`): All URLs that have been crawled
 - **knowledge_base** (`List[CrawlResult]`): Collection of crawled pages with content