Replace dashes with underscores in index credential variables (#8452)

## Summary

Closes #8448.

crates/uv-auth/src/credentials.rs

@@ -146,7 +146,17 @@ impl Credentials {
     /// For example, given a name of `"pytorch"`, search for `UV_INDEX_PYTORCH_USERNAME` and
     /// `UV_INDEX_PYTORCH_PASSWORD`.
     pub fn from_env(name: &str) -> Option<Self> {
-        let name = name.to_uppercase();
+        // Convert to uppercase, and replace any non-alphanumeric characters with underscores.
+        let name = name
+            .chars()
+            .map(|c| {
+                if c.is_ascii_alphanumeric() {
+                    c.to_ascii_uppercase()
+                } else {
+                    '_'
+                }
+            })
+            .collect::<String>();
         let username = std::env::var(EnvVars::index_username(&name)).ok();
         let password = std::env::var(EnvVars::index_password(&name)).ok();
         if username.is_none() && password.is_none() {

crates/uv/tests/it/lock.rs

@@ -6817,7 +6817,7 @@ fn lock_env_credentials() -> Result<()> {
         build-backend = "setuptools.build_meta"
 
         [[tool.uv.index]]
-        name = "proxy"
+        name = "internal-proxy"
         url = "https://pypi-proxy.fly.dev/basic-auth/simple"
         default = true
         "#,
@@ -6838,8 +6838,8 @@ fn lock_env_credentials() -> Result<()> {
 
     // Provide credentials via environment variables.
     uv_snapshot!(context.filters(), context.lock()
-        .env(EnvVars::index_username("PROXY"), "public")
-        .env(EnvVars::index_password("PROXY"), "heron"), @r###"
+        .env(EnvVars::index_username("INTERNAL_PROXY"), "public")
+        .env(EnvVars::index_password("INTERNAL_PROXY"), "heron"), @r###"
     success: true
     exit_code: 0
     ----- stdout -----