## Summary
resolves https://github.com/astral-sh/uv/issues/5915, not entirely sure
if `manylinux_compatible` should be a separate field in the JSON
returned by the interpreter or there's some way to use the existing
`platform` for it.
## Test Plan
ran the below
```
rm -rf .venv
target/debug/uv venv
# commenting out the line below triggers the change..
# target/debug/uv pip install no-manylinux
target/debug/uv pip install cryptography --no-cache
```
is there an easy way to add this into the existing snapshot-based test
suite? looking around to see if there's a way that doesn't involve
something implementation-dependent like mocks.
~update: i think the output does differ between these two, so probably
we can use that.~ i lied - that "building..." output seems to be
discarded.
Whew this is a lot.
The user-facing changes are:
- `uv toolchain` to `uv python` e.g. `uv python find`, `uv python
install`, ...
- `UV_TOOLCHAIN_DIR` to` UV_PYTHON_INSTALL_DIR`
- `<UV_STATE_DIR>/toolchains` to `<UV_STATE_DIR>/python` (with
[automatic
migration](https://github.com/astral-sh/uv/pull/4735/files#r1663029330))
- User-facing messages no longer refer to toolchains, instead using
"Python", "Python versions" or "Python installations"
The internal changes are:
- `uv-toolchain` crate to `uv-python`
- `Toolchain` no longer referenced in type names
- Dropped unused `SystemPython` type (previously replaced)
- Clarified the type names for "managed Python installations"
- (more little things)
