feat!: Add apiKey support to API requests

- Introduced `apiKey` field for secure authentication in configuration and API requests.
- Updated clear and task APIs to accept enhanced request objects.
- Added required tests and assertions for `apiKey` handling across all request types.
- Refactored HTTP operations to include `apiKey` in request headers.
- Introduced new classes for managing authentication details.

Fixes #187

Signed-off-by: Eric Deandrea <[email protected]>

Author: edeandrea

docs/src/doc/docs/docling-serve/serve-api.md

@@ -85,11 +85,7 @@ System.out.println(response.getDocument().getMarkdownContent());
 
 ### The `DoclingServeApi` interface
 
-Defined in `ai.docling.serve.api.DoclingServeApi`, this interface exposes two primary operations:
-
-- `health()` → returns a `HealthCheckResponse` with service status.
-- `convertSource(request)` → submits one or more sources plus options and an optional target,
-  returning `ConvertDocumentResponse`.
+Defined in `ai.docling.serve.api.DoclingServeApi`, this interface exposes many operations:
 
 Any HTTP or non-HTTP implementation can implement this interface. The reference implementation is
 provided by the `docling-serve-client` module.

docs/src/doc/docs/docling-serve/serve-client.md

@@ -134,6 +134,7 @@ DoclingServeApi noisy = DoclingServeClientBuilderFactory.newBuilder()
     .baseUrl("http://localhost:8000")
     .logRequests()
     .logResponses()
+    .prettyPrint()
     .build();
 ```