Send llm events to snowflake too (#21091)

Closes #ISSUE

Release Notes:

- N/A

crates/collab/src/api.rs

@@ -61,6 +61,39 @@ impl std::fmt::Display for CloudflareIpCountryHeader {
     }
 }
 
+pub struct SystemIdHeader(String);
+
+impl Header for SystemIdHeader {
+    fn name() -> &'static HeaderName {
+        static SYSTEM_ID_HEADER: OnceLock<HeaderName> = OnceLock::new();
+        SYSTEM_ID_HEADER.get_or_init(|| HeaderName::from_static("x-zed-system-id"))
+    }
+
+    fn decode<'i, I>(values: &mut I) -> Result<Self, axum::headers::Error>
+    where
+        Self: Sized,
+        I: Iterator<Item = &'i axum::http::HeaderValue>,
+    {
+        let system_id = values
+            .next()
+            .ok_or_else(axum::headers::Error::invalid)?
+            .to_str()
+            .map_err(|_| axum::headers::Error::invalid())?;
+
+        Ok(Self(system_id.to_string()))
+    }
+
+    fn encode<E: Extend<axum::http::HeaderValue>>(&self, _values: &mut E) {
+        unimplemented!()
+    }
+}
+
+impl std::fmt::Display for SystemIdHeader {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
 pub fn routes(rpc_server: Arc<rpc::Server>) -> Router<(), Body> {
     Router::new()
         .route("/user", get(get_authenticated_user))