An untitled note kept because something else wrote into it can't be reopened with Cmd+Shift+T

What happens

1. Create a new untitled markdown note and don't type in it.
2. Have an agent or another program write text into its untitled.md.
3. Close the tab, then press Cmd+Shift+T.

Actual: the file stays on disk, but Cmd+Shift+T doesn't bring the tab back. Close All behaves the same way. Expected: Cmd+Shift+T reopens the note like any other closed tab.

Found in review of #23768. It follows from the code; I haven't reproduced it in the app yet. Notes saved from Orca's own editor aren't affected: they're reopenable.

Why

• When a tab closes, closeFile in src/renderer/src/store/slices/editor/actions/close-file-action.ts decides right away whether to add it to the reopen history. An untitled note that looks untouched (no unsaved text, never saved from the editor) is left out, because it's about to be deleted. closeAllFiles in recently-closed-editor-tabs.ts does the same.
• #23768 added a check in untitled-file-cleanup.ts that looks at the file on the machine that owns it and keeps it if it has content. That check finishes after the close, so the reopen history has already skipped the tab.
• The reopen history is shared by terminal, browser and editor tabs, and its order decides which tab Cmd+Shift+T brings back.

Acceptance

• Cmd+Shift+T reopens an untitled note that was kept because it had content, after both a normal close and Close All.
• Cmd+Shift+T still reopens tabs in the right order when terminal, browser or other editor tabs were closed around it.
• Covered for local and SSH/remote workspaces.
• A test that fails if the fix is reverted.