Allow entering an interpreter path from the project view environment selector #1919

Feature request

When selecting a Python environment from the project view, I want an option to manually enter an interpreter path, similar to the Python: Select Interpreter command's Enter interpreter path... option.

Current behavior

From the project view's "Select a Python Environment" flow, I only see discovered environments. If my virtual environment is not discovered, there does not appear to be a way to paste or type the interpreter path directly.

Desired behavior

Add an "Enter interpreter path..." option to the project view environment selector so users can provide a path such as:

/path/to/project/.venv/bin/python

This would make the project view flow consistent with the Command Palette flow and help when environments created by tools like uv are not immediately discovered.

Why this matters

Users who create virtual environments manually or with tools such as uv may already know the exact interpreter path. Requiring discovery or a separate Command Palette workflow makes the project view less useful and harder to recover from when auto-discovery misses an environment.