fix: metrics on posthog (#6024)

Co-authored-by: Zane Staggs <zane@squareup.com>
Co-authored-by: Zane <75694352+zanesq@users.noreply.github.com>

crates/goose-cli/src/session/builder.rs

@@ -248,6 +248,8 @@ pub struct SessionSettings {
 }
 
 pub async fn build_session(session_config: SessionBuilderConfig) -> CliSession {
+    goose::posthog::set_session_context("cli", session_config.resume);
+
     let config = Config::global();
 
     let (saved_provider, saved_model_config) = if session_config.resume {