Show dedicated message for tools with no entrypoints (#4694)

## Summary

Closes https://github.com/astral-sh/uv/issues/4688.

## Test Plan

```
❯ cargo run tool install ruff
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.14s
     Running `target/debug/uv tool install ruff`
warning: `uv tool install` is experimental and may change without warning.
Resolved 1 package in 136ms
Installed 1 package in 3ms
 + ruff==0.5.0
No entrypoints to install for tool `ruff`
```

crates/uv/src/commands/tool/install.rs

@@ -200,6 +200,13 @@ pub(crate) async fn install(
         })
         .collect::<BTreeSet<_>>();
 
+    if target_entry_points.is_empty() {
+        // Clean up the environment we just created
+        installed_tools.remove_environment(&name)?;
+
+        bail!("No entry points found for tool `{name}`");
+    }
+
     // Check if they exist, before installing
     let mut existing_entry_points = target_entry_points
         .iter()
@@ -232,7 +239,6 @@ pub(crate) async fn install(
         )
     }
 
-    // TODO(zanieb): Handle the case where there are no entrypoints
     for (name, source_path, target_path) in &target_entry_points {
         debug!("Installing `{name}`");
         #[cfg(unix)]
@@ -250,7 +256,7 @@ pub(crate) async fn install(
             .join(", ")
     )?;
 
-    debug!("Adding receipt for tool `{name}`",);
+    debug!("Adding receipt for tool `{name}`");
     let installed_tools = installed_tools.init()?;
     let tool = Tool::new(
         requirements,

crates/uv/tests/tool_install.rs

@@ -858,3 +858,28 @@ fn tool_install_xdg_bin_home() {
         .child(format!("black{}", std::env::consts::EXE_SUFFIX))
         .assert(predicate::path::exists());
 }
+
+/// Test installing a tool that lacks entrypoints
+#[test]
+fn tool_install_no_entrypoints() {
+    let context = TestContext::new("3.12").with_filtered_exe_suffix();
+    let tool_dir = context.temp_dir.child("tools");
+    let bin_dir = context.temp_dir.child("bin");
+
+    uv_snapshot!(context.filters(), context.tool_install()
+        .arg("iniconfig")
+        .env("UV_TOOL_DIR", tool_dir.as_os_str())
+        .env("XDG_BIN_HOME", bin_dir.as_os_str()), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: `uv tool install` is experimental and may change without warning.
+    Resolved 1 package in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + iniconfig==2.0.0
+    error: No entry points found for tool `iniconfig`
+    "###);
+}