[Feature]: Workspace notes — global/cross-workspace memo (per-worktree Comment field already exists)

### Problem or use case

When I log out of a coding session and log back in, I need to remember what changes I made so I can test them. Right now I just jot it down in a notepad app. Does Orca have (or could it add) a built-in notes feature tied to the workspace/repo itself — not a .txt file sitting in the code directory — so I can leave myself reminders about what to test, scoped to that project?"

### Proposed solution

a built-in notes feature tied to the workspace/repo itself — not a .txt file sitting in the code directory

### Alternatives or additional context

_No response_