Allow for unnormalized names in the `METADATA` file (#16547) (#16548)

## Summary

Deserialize project name into both a String and a ProjectName, this way
we can keep using the normalized name elsewhere while respecting the
original name from the `pyproject.toml` file

This PR addresses issue #16547

## Test Plan

I added a new test for this, and I ran the test suite in the
`metadata.rs` file.

---------

Co-authored-by: Charlie Marsh <charlie.r.marsh@gmail.com>

crates/uv-build-backend/src/metadata.rs

@@ -6,7 +6,7 @@ use std::path::{Path, PathBuf};
 use std::str::FromStr;
 
 use itertools::Itertools;
-use serde::Deserialize;
+use serde::{Deserialize, Deserializer};
 use tracing::{debug, trace, warn};
 use version_ranges::Ranges;
 use walkdir::WalkDir;
@@ -105,6 +105,26 @@ pub fn check_direct_build(source_tree: &Path, name: impl Display) -> bool {
     }
 }
 
+/// A package name as provided in a `pyproject.toml`.
+#[derive(Debug, Clone)]
+struct VerbatimPackageName {
+    /// The package name as given in the `pyproject.toml`.
+    given: String,
+    /// The normalized package name.
+    normalized: PackageName,
+}
+
+impl<'de> Deserialize<'de> for VerbatimPackageName {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let given = String::deserialize(deserializer)?;
+        let normalized = PackageName::from_str(&given).map_err(serde::de::Error::custom)?;
+        Ok(Self { given, normalized })
+    }
+}
+
 /// A `pyproject.toml` as specified in PEP 517.
 #[derive(Deserialize, Debug, Clone)]
 #[serde(
@@ -123,7 +143,7 @@ pub struct PyProjectToml {
 
 impl PyProjectToml {
     pub(crate) fn name(&self) -> &PackageName {
-        &self.project.name
+        &self.project.name.normalized
     }
 
     pub(crate) fn version(&self) -> &Version {
@@ -456,7 +476,7 @@ impl PyProjectToml {
 
         Ok(Metadata23 {
             metadata_version: metadata_version.to_string(),
-            name: self.project.name.to_string(),
+            name: self.project.name.given.clone(),
             version: self.project.version.to_string(),
             // Not supported.
             platforms: vec![],
@@ -579,7 +599,7 @@ impl PyProjectToml {
 #[serde(rename_all = "kebab-case")]
 struct Project {
     /// The name of the project.
-    name: PackageName,
+    name: VerbatimPackageName,
     /// The version of the project.
     version: Version,
     /// The summary description of the project in one line.
@@ -856,6 +876,28 @@ mod tests {
         formatted
     }
 
+    #[test]
+    fn uppercase_package_name() {
+        let contents = r#"
+            [project]
+            name = "Hello-World"
+            version = "0.1.0"
+
+            [build-system]
+            requires = ["uv_build>=0.4.15,<0.5.0"]
+            build-backend = "uv_build"
+        "#;
+        let pyproject_toml = PyProjectToml::parse(contents).unwrap();
+        let temp_dir = TempDir::new().unwrap();
+
+        let metadata = pyproject_toml.to_metadata(temp_dir.path()).unwrap();
+        assert_snapshot!(metadata.core_metadata_format(), @r"
+        Metadata-Version: 2.3
+        Name: Hello-World
+        Version: 0.1.0
+        ");
+    }
+
     #[test]
     fn valid() {
         let temp_dir = TempDir::new().unwrap();