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-distribution/src/lib.rs

@@ -0,0 +1,16 @@
+pub use distribution_database::DistributionDatabase;
+pub use download::{BuiltWheel, DiskWheel, LocalWheel};
+pub use error::Error;
+pub use index::{BuiltWheelIndex, RegistryWheelIndex};
+pub use reporter::Reporter;
+pub use source::SourceDistCachedBuilder;
+pub use unzip::Unzip;
+
+mod distribution_database;
+mod download;
+mod error;
+mod index;
+mod locks;
+mod reporter;
+mod source;
+mod unzip;