[Feature]: Allow "Open" to launch a custom/user-defined application

[seniru-dilmith]

Before submitting

• I searched existing issues and did not find a duplicate.
• I am describing a concrete problem or use case, not just a vague idea.

Area
apps/desktop

Problem or use case
The "Open" dropdown currently only lists a fixed set of applications (VS Code, CLion, PyCharm, RustRover, Files). If a user's preferred editor or tool isn't one of these, there's no way to launch the project with it they have to fall back to manually locating and opening the folder outside the app.

This is limiting for anyone using editors or tools outside the pre-baked list, e.g. Zed, Sublime Text, Neovim (via a terminal wrapper), Android Studio, Cursor, or internal/company-specific tooling.

Proposed solution
Add a "Custom application..." entry at the bottom of the "Open" dropdown that lets the user specify the path/command of an arbitrary application to open the project with.

Behavior:

• Selecting it opens a native file/app picker so the user can point to an executable.
• Once chosen, the entry is saved so it appears in the "Open" list going forward, like a first-class entry alongside the built-in apps.
• The app should be launched with the project's root path as an argument, consistent with how the existing entries behave.

Why this matters
Not everyone uses the same fixed list of IDEs. Supporting a custom application removes a hard limitation for users on less common editors and avoids forcing a detour through the file system every time.

Smallest useful scope

• Add a "Custom application" item to the Open dropdown.
• Prompt for an executable path via a native picker.
• Launch it with the project path as an argument.
• Persist the choice so it's remembered as a normal entry for next time.

No new open/no-existing-defaults behavior needs to change. This only adds an additional option.

Alternatives considered

• Manually opening the project folder and launching the app separately: works today but breaks the one-click workflow the Open menu provides for every other app.
• Requesting each individual missing editor be added as a hardcoded option: doesn't scale and still leaves out anyone on a less common tool.

Risks or tradeoffs
Needs to handle invalid/missing executable paths gracefully (e.g. app was moved or uninstalled since being set). Should probably allow removing/editing a saved custom entry.

Contribution

• I would be open to helping implement this.

[kethma-sansiluni]

Yeah! This will be very useful