Usability and feature refinement for openidea's Agent functionality

This issue provides direct, actionable feedback on `openidea`'s Agent usability, highlighting three key pain points. First, the 'is not a git repository' restriction limits Agent utility in non-Git contexts, hindering flexibility. Second, the inability to manually close the 'Changes' dialog within the Agent interface reduces workspace efficiency and user control. Third, the suggestion to integrate the AI dialog into the 'Agents panel' indicates a desire for better UI organization and a more cohesive Agent experience. Collectively, these points reveal a need for improved flexibility, UI control, and logical grouping of AI-related features. Addressing these refinements is crucial for enhancing the developer experience, reducing friction, and ensuring the Agent functionality is perceived as a seamless, integrated component rather than an isolated or restrictive tool.