[comp datarouter] Implementation completion

## What

Complete the Implementation (`wp__sw_implementation`) for the component datarouter: formalize existing design files in `logging/score/datarouter/doc/design/` with `document::` and `:realizes: wp__sw_implementation`. The implementation includes source code, detailed design, and SW configuration.

## How

**Process step:** [wf__sw_detailed_design](https://eclipse-score.github.io/process_description/main/process_areas/implementation/implementation_workflow.html#wf__sw_detailed_design)
Existing artifact: [[datarouter/doc/design/](logging/score/datarouter/doc/design/)]([datarouter/doc/design/](logging/score/datarouter/doc/design/))

## Definition of Done

All criteria of the [Implementation Checklist](https://eclipse-score.github.io/process_description/main/process_areas/implementation/guidance/implementation_checklist.html) are met.

## Template & Folder Structure

- **Template:** [Detailed Design Template](https://eclipse-score.github.io/module_template/main/score/component_example/docs/detailed_design/detailed_design_example.html)
- **Folder:** `score//docs/detailed_design/` – see [Module Folder Structure](https://eclipse-score.github.io/module_template/main/index.html#module-layout)

*Please apply the linked template and folder structure to ensure consistency across the S-CORE project.*