Improve logging during interpreter discovery

[zanieb]

❯ VIRTUAL_ENV=.venv cargo run -q -- pip install anyio -v
DEBUG Searching for interpreter that fulfills Python @ default in virtual environments
DEBUG Found Python interpreter cpython 3.12.3 at `.venv/bin/python` (active virtual environment)
DEBUG Using Python 3.12.3 environment at .venv/bin/python
DEBUG Trying to lock if free: .venv/.lock
DEBUG Requirement satisfied: anyio
DEBUG Requirement satisfied: idna>=2.8
DEBUG Requirement satisfied: sniffio>=1.1
DEBUG All editables satisfied: 
Audited 1 package in 14ms

instead of

❯ VIRTUAL_ENV=.venv cargo run -q -- pip install anyio -v
DEBUG Searching for interpreter that fulfills Python @ default
DEBUG Searching for interpreter that fulfills Python @ default
INFO Found active virtual environment (via VIRTUAL_ENV) at: .venv
DEBUG Found a virtual environment at: /Users/zb/workspace/uv/.venv
DEBUG Using Python 3.12.3 environment at .venv/bin/python
DEBUG Trying to lock if free: .venv/.lock
DEBUG Requirement satisfied: anyio
DEBUG Requirement satisfied: idna>=2.8
DEBUG Requirement satisfied: sniffio>=1.1
DEBUG All editables satisfied: 
Audited 1 package in 16ms

[charliermarsh]

What is Python @ default?

Should Found Python interpreter cpython 3.12.3 perhaps be something like Found cpython@3.12.3 at...? "Python interpreter {impl}" is maybe a bit redundant?

[zanieb]

"Python @ default" was resolved / removed in #3789

The implementation name display is being changed in #3791 — I do agree it feels a little redundant though. Let me rebase onto main and tweak a bit more.

[zanieb]

Now it looks like

DEBUG Searching for interpreter that fulfills any Python in virtual environments
DEBUG Found CPython 3.12.3 at `.venv/bin/python` (active virtual environment)
DEBUG Using Python 3.12.3 environment at .venv/bin/python

[zanieb]

Specialized the search message per request kind so we can do a little better e.g.

❯ VIRTUAL_ENV=.venv cargo run -q -- pip install anyio -v
DEBUG Searching for Python interpreter in virtual environments
DEBUG Found CPython 3.12.3 at `.venv/bin/python` (active virtual environment)
DEBUG Using Python 3.12.3 environment at .venv/bin/python

❯ cargo run -q -- pip install anyio -v --python cpython
DEBUG Searching for a CPython interpreter in all sources
DEBUG Found CPython 3.12.3 at `/Users/zb/workspace/uv/.venv/bin/python` (virtual environment)
DEBUG Using Python 3.12.3 environment at .venv/bin/python

❯ cargo run -q -- pip install anyio -v --python .venv
DEBUG Checking for Python interpreter in directory .venv
DEBUG Using Python 3.12.3 environment at .venv/bin/python

❯ cargo run -q -- pip install anyio -v --python .venv/bin/python
DEBUG Checking for Python interpreter at path .venv/bin/python
DEBUG Using Python 3.12.3 environment at .venv/bin/python