Rename to uv (#1302)

First, replace all usages in files in-place. I used my editor for this.
If someone wants to add a one-liner that'd be fun.

Then, update directory and file names:

```
# Run twice for nested directories
find . -type d -print0 | xargs -0 rename s/puffin/uv/g
find . -type d -print0 | xargs -0 rename s/puffin/uv/g

# Update files
find . -type f -print0 | xargs -0 rename s/puffin/uv/g
```

Then add all the files again

```
# Add all the files again
git add crates
git add python/uv

# This one needs a force-add
git add -f crates/uv-trampoline
```

crates/uv-resolver/src/resolution_mode.rs

@@ -0,0 +1,45 @@
+use rustc_hash::FxHashSet;
+
+use pep508_rs::Requirement;
+use uv_normalize::PackageName;
+
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
+#[cfg_attr(feature = "clap", derive(clap::ValueEnum))]
+pub enum ResolutionMode {
+    /// Resolve the highest compatible version of each package.
+    #[default]
+    Highest,
+    /// Resolve the lowest compatible version of each package.
+    Lowest,
+    /// Resolve the lowest compatible version of any direct dependencies, and the highest
+    /// compatible version of any transitive dependencies.
+    LowestDirect,
+}
+
+/// Like [`ResolutionMode`], but with any additional information required to select a candidate,
+/// like the set of direct dependencies.
+#[derive(Debug, Clone)]
+pub(crate) enum ResolutionStrategy {
+    /// Resolve the highest compatible version of each package.
+    Highest,
+    /// Resolve the lowest compatible version of each package.
+    Lowest,
+    /// Resolve the lowest compatible version of any direct dependencies, and the highest
+    /// compatible version of any transitive dependencies.
+    LowestDirect(FxHashSet<PackageName>),
+}
+
+impl ResolutionStrategy {
+    pub(crate) fn from_mode(mode: ResolutionMode, direct_dependencies: &[Requirement]) -> Self {
+        match mode {
+            ResolutionMode::Highest => Self::Highest,
+            ResolutionMode::Lowest => Self::Lowest,
+            ResolutionMode::LowestDirect => Self::LowestDirect(
+                direct_dependencies
+                    .iter()
+                    .map(|requirement| requirement.name.clone())
+                    .collect(),
+            ),
+        }
+    }
+}