Fetch a single Azure DevOps work item by integer ID. Returns id, browse URL, title, description (HTML stripped to plain text), work item type, state, priority, assignee, creator, tags, area path, iteration path, timestamps, acceptanceCriteria (plain text), steps (Test Case items: [{action, expected}] with shared steps expanded and @params filled from the first data row), and links (URLs from description anchors and Hyperlink relations, deduped; each has a kind — "figma" marks a design mockup). TIP: links with kind 'figma' are design mockups — open them with figma_frame_image / figma_frame_spec to check the build against the design. Uses the calling user's stored AzDO credential — does not accept inline credentials. Returns an actionable error if AzDO is not configured.