fix(ai): allowing whitespace between escape and json markdown

[whitdog47]

This PR enhances the JSON cleanup logic by switching from simple string replaces to a regex-based approach that tolerates whitespace around Markdown code fences.

[Copilot]

Pull Request Overview

This PR switches JSON cleanup from manual string operations to a regex-based helper that tolerates extra whitespace around Markdown fences.

• Added clean_json_markdown with a single regex to strip code fences and optional language specifiers.
• Replaced inline fence-stripping logic in generate_case_signal_summary and get_tag_recommendations with the new helper.

Comments suppressed due to low confidence (2)

src/dispatch/ai/service.py:105

• Add unit tests for clean_json_markdown to verify it correctly handles various whitespace scenarios, optional language tags, and escaped newline sequences.

def clean_json_markdown(json_string: str) -> str:

src/dispatch/ai/service.py:567

• The previous logic also replaced escaped newlines and flattened whitespace before validation. Ensure model_validate_json can handle raw output without those steps or reintroduce necessary newline/whitespace cleanup.

        return TagRecommendationResponse.model_validate_json(clean_json_markdown(result))