chore: refactor internal structure

[ByteAurora]

This PR improves CodeXP internal structure and contributor-facing project hygiene while preserving existing user-facing behavior.

Changes

• Add contributor documentation and repository hygiene updates for KDoc, AI-assisted development notes, AI local file ignores, and release process guidance.
• Separate progress domain logic from IntelliJ service dispatch.
• Scope overlay UI lifecycle to project windows and dispose message bus/UI resources properly.
• Clean plugin descriptor inspections and clarify presentation package structure.

Please check the build workflows pass before merging.