Closes #61346

# Objective

At startup, a synchronous `try_recv` decides whether to restore the
session. On a macOS cold launch the CLI request arrives via
`application:openURLs:`, which AppKit dispatches only *after* the
startup closure returns, so the check finds nothing, session restore
begins, and the request lands moments later on the post-startup path.

Both behaviors are individually correct: a user with
`restore_on_startup: "last_session"` wants their session back, and the
requested file should open. The defect is that they race, the CLI open
runs its existing-window matching before restore has placed any windows,
finds nothing to reuse, and opens a redundant window.

## Solution

Make the post-startup open loop wait for restore to settle before
handling a request, so `find_existing_workspace` sees the restored
windows and honors `cli_default_open_behavior`.

The wait races full restore completion against the first window being
placed, so a slow or hung remote-workspace restore can't block a local
open. No timeouts involved, the fix is ordering, not delay :).

## Testing

**Steps**:
1. disable & enable the setting `close windows when quiting an
application` in macos itself in `desktop & dock` section
2. create a bundled Zed app
3. install cli binary to actually test the change
4. Follow any of the steps inside the before/after video's to test all
the cases we have

I tested this with a manual prod build using a custom script that
bundles Zed as a preview app. So I could actually test the cli baviour
since it works different for non-bundled builds. So the easiest way to
test this would be to run bundling on this PR and install the cli binary
to actually test it with the fix included.

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [ ] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

## Showcase

<details>

<summary>**Disabled** Close windows when quiting an
application</summary>

**before** (disabled apps on close & `add to existing window` cli
bahavior)


https://github.com/user-attachments/assets/b497130b-3432-4fa8-9fbe-70c6f63d165e

**After** (disabled apps on close & `add to existing window` cli
bahavior)


https://github.com/user-attachments/assets/354657f7-8dfe-4beb-9dd4-2bb615cb912c

**After** (disabled apps on close & `open a new window` cli bahavior)


https://github.com/user-attachments/assets/07fc3062-89a3-4e2a-811e-296533feaad7

</details>

<details>

<summary>**Enabled** Close windows when quiting an application
(unchanged)</summary>

**After** (enabled** apps on close & `add to existing window` cli
bahavior (**unchanged**))


https://github.com/user-attachments/assets/445f1d3a-2987-46b1-9bfb-b2d61894ddec

**After** (enabled apps on close & `open a new window` cli bahavior
(**unchanged**))


https://github.com/user-attachments/assets/c3078b0d-7fb4-42db-9dea-095439e23830

</details>

---

Release Notes:

- Fixed an extra window opening on macOS when launching Zed from the CLI
with session restore enabled