sub_package in Dioxus.toml has no effect

**Problem**

Setting sub_package under [application] appears to do nothing working with workspaces.

I investigated further and found no mention of sub_package in the git repository.

This is preventing me from being able to use https://github.com/DioxusLabs/deploy-action

**Steps To Reproduce**

Steps to reproduce the behavior:

Virtual workspaces with more than one package.

set sub_package to:

```
[application]
sub_package = "package_name"
```

```dx --package package_name bundle``` works

```dx bundle``` does not

**Expected behavior**

In a virtual workspace it would select the package I want to build from using the "dx" command.

Cargo build picks the right package, but "dx" does not.

**Environment:**

- Dioxus version: dioxus 0.7.0-rc.0 (a519fba)
- Rust version: rustc 1.90.0-nightly (f8e355c23 2025-07-27)
- OS info: MacOs
- App platform: N/A

**Questionnaire**
I'm interested in fixing this myself but don't know where to start.