Cannot Close A Project

Version and Platform (required):

• Binary Ninja Version: 5.1.7468-dev
• Edition: Ultimate
• OS: macOS
• OS Version: 15.5
• CPU Architecture: x64

Bug Description:
Once one project is open, it cannot be closed. Only a different project can be opened. This affects how new files are opened. If a project is open, new files will be opened in a separate instance of binja. This happens even if you X out of the project's tab. You can see that a project is still open in the lower left corner of the window.

Steps To Reproduce:

1. Open a project.
2. Hit the X to close the project via the tab
3. Notice in the lower left corner, the project name is still shown.
4. Use the Open, Open with options, or Triage buttons to open a new file.
5. Notice that a whole new instance of binja has been created.
6. Notice that the instance of binja with the project open is still there in the background with nothing in it and no tabs open.

Expected Behavior:
There should be a way to close a project (or when X'ing out of the project tab the project should close). Once the project is closed, new files open in the same context as the open window.

Reproduce the workflow on macOS: open a project, close its tab with X, then use Open, Open with, or Triage. Trace the project and tab-close handling to determine why the project remains shown in the lower-left corner and a new instance opens. Done means closing the project clears the project context and new files open in the same window.