Use distinct user agents in agent eval and zeta-cli (#35897)

Agent eval now also uses a proper Zed version

Release Notes:

- N/A

crates/eval/build.rs

@@ -0,0 +1,14 @@
+fn main() {
+    let cargo_toml =
+        std::fs::read_to_string("../zed/Cargo.toml").expect("Failed to read crates/zed/Cargo.toml");
+    let version = cargo_toml
+        .lines()
+        .find(|line| line.starts_with("version = "))
+        .expect("Version not found in crates/zed/Cargo.toml")
+        .split('=')
+        .nth(1)
+        .expect("Invalid version format")
+        .trim()
+        .trim_matches('"');
+    println!("cargo:rustc-env=ZED_PKG_VERSION={}", version);
+}