[client] Declare the xdg-utils dependency for the netbird-ui packages (#7126)

## Describe your changes

The UI shells out to xdg-open to launch the external browser for the SSO
verification page, which the embedded webview cannot open inline, and to
reveal the debug bundle in the file manager.

client/ui/build/linux/nfpm/nfpm.yaml lists xdg-utils for every package
format, but the released packages are built from the goreleaser configs,
where it was missing: the GTK and WebKitGTK dependencies carried over
and xdg-utils did not. Add it to all four nfpm dependency lists.

## Issue ticket number and link

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## Stack

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### Checklist
- [x] Is it a bug fix
- [ ] Is a typo/documentation fix
- [ ] Is a feature enhancement
- [ ] It is a refactor
- [ ] Created tests that fail without the change (if possible)
- [ ] I ran and tested this change locally — I did not rely on CI to
find out whether it works
- [ ] This PR has a single purpose (not a fix + refactor + feature in
one)
- [ ] This change is a trivial fix, **OR** it links an issue the NetBird
team agreed on beforehand. Changes to the public API, gRPC protocols,
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## Documentation
Select exactly one:

- [ ] I added/updated documentation for this change
- [x] Documentation is **not needed** for this change (explain why)

### Docs PR URL (required if "docs added" is checked)
Paste the PR link from https://github.com/netbirdio/docs here:

https://github.com/netbirdio/docs/pull/__


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Bug Fixes**
* Added required desktop integration support to Debian and RPM packages.
* Ensured GTK3 packages include the same runtime support for opening
links and files through the system.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.goreleaser_ui.yaml

@@ -96,6 +96,7 @@ nfpms:
       - netbird (>= 0.75.0)
       - libgtk-4-1 (>= 4.14)
       - libwebkitgtk-6.0-4
+      - xdg-utils
 
   - maintainer: Netbird <dev@netbird.io>
     description: Netbird client UI.
@@ -119,6 +120,7 @@ nfpms:
       - netbird >= 0.75.0
       - (gtk4 >= 4.14 or libgtk-4-1 >= 4.14)
       - (webkitgtk6.0 or libwebkitgtk-6_0-4)
+      - xdg-utils
 
     rpm:
       signature:

.goreleaser_ui_gtk3.yaml

@@ -71,6 +71,7 @@ nfpms:
       - netbird (>= 0.75.0)
       - libgtk-3-0
       - libwebkit2gtk-4.1-0
+      - xdg-utils
 
   - maintainer: Netbird <dev@netbird.io>
     description: Netbird client UI.
@@ -95,6 +96,7 @@ nfpms:
       - netbird >= 0.75.0
       - (gtk3 or libgtk-3-0)
       - (webkit2gtk4.1 or libwebkit2gtk-4_1-0)
+      - xdg-utils
 
     rpm:
       signature: