Allow direct task creation without requiring comment-to-task conversion

[Philipp0205]

Summary

Users should be able to create tasks immediately during code review without first creating a comment and then converting it to a task.

User Story

As a code reviewer, I want to create tasks directly on code lines, so that I can quickly flag action items without the extra step of converting comments.

Proposed Solution

• Add "Create Task" action alongside "Add Comment" in inline review UI
• Provide task-specific fields (title, description, checkbox state)
• Tasks are visually distinguished from comments (e.g., checkbox icon)
• Support marking tasks as complete/incomplete
• Sync task state with provider APIs (GitHub task lists, Bitbucket tasks)

Acceptance Criteria

• "Create Task" action available in code review context menu
• Tasks can be created without first creating a comment
• Task UI includes checkbox and description fields
• Tasks are visually distinct from comments
• Users can toggle task completion status
• Tasks sync correctly with GitHub and Bitbucket
• Existing comment-to-task conversion still works

Technical Considerations

• GitHub: Use task list markdown syntax in comment body (- [ ] Task item)
• Bitbucket: Use tasks API endpoints for task creation
• Update PullRequestComment model to include task metadata
• Add task-specific UI widgets to comment viewers
• Handle task state synchronization during refresh
• Consider filtering/sorting by task completion status