## Summary
The function `find_in_directory` joins `uv.toml`. The initial join in
`user` is redundant.
Also a small comment fix.
## Test Plan
Not really sure how to test this. Please suggest if any tests need to be
added.
Adds hidden `--preview` / `--no-preview` flags with `UV_PREVIEW`
environment variable support. Copies the `PreviewMode` type from Ruff.
Does a little bit of extra work to port `uv run` to the new settings
model.
Note we allow `uv run` invocations without preview and only use its
presence to toggle an experimental warning.
## Test plan
```
❯ cargo run -q -- run --no-workspace -- python --version
warning: `uv run` is experimental and may change without warning.
Python 3.12.2
❯ cargo run -q -- run --no-workspace --preview -- python --version
Python 3.12.2
❯ UV_PREVIEW=1 cargo run -q -- run --no-workspace -- python --version
Python 3.12.2
```
## Summary
Enables `uv` to read configuration from (e.g.)
`/Users/crmarsh/.config/uv/uv.toml` on macOS and Linux, and
`C:\Users\Charlie\AppData\Roaming\uv\uv.toml` on Windows.
This differs slightly from Ruff, which uses the `Application Support`
directory on macOS. But I've deviated here. based on the preferences
expressed in https://github.com/astral-sh/ruff/issues/10739.
## Summary
This PR adds the structs and logic necessary to respect settings from
the workspace. It's a ton of code, but it's mostly mechanical. And,
believe it or not, I pulled out a few refactors in advance to trim down
the code and complexity.
The highlights are:
- All CLI arguments are now `Option`, so that we can detect whether they
were provided (i.e., we can't let Clap fill in the defaults).
- We now have a `*Settings` struct for each command, which merges the
CLI and workspace options (e.g., `PipCompileSettings`).
I've only implemented `PipCompileSettings` for now. If approved, I'll
implement the others prior to merging, but it's very mechanical and I
both didn't want to do the conversion prior to receiving feedback _and_
realized it would make the PR harder to review.
## Summary
This PR adds basic struct definitions along with a "workspace" concept
for discovering settings. (The "workspace" terminology is used to match
Ruff; I did not invent it.)
A few notes:
- We discover any `pyproject.toml` or `uv.toml` file in any parent
directory of the current working directory. (We could adjust this to
look at the directories of the input files.)
- We don't actually do anything with the configuration yet; but those
PRs are large and I want this to be reviewed in isolation.
