refactor: split telemetry module

tests/telemetry.rs

@@ -0,0 +1,18 @@
+use pokedex_api::telemetry::Telemetry;
+use std::time::Duration;
+
+#[test]
+fn records_http_and_upstream_metrics_in_prometheus_text_format() {
+    let telemetry = Telemetry::new("test-service");
+    let metrics = telemetry.metrics();
+
+    metrics.record_http_request("GET", "/pokemon/{name}", 200, Duration::from_millis(10));
+    metrics.record_upstream_request("pokeapi", "pokemon_species", true, Duration::from_millis(5));
+    let rendered = telemetry
+        .render_prometheus()
+        .expect("metrics should render as text");
+
+    assert!(rendered.contains("http_server_requests"));
+    assert!(rendered.contains("upstream_client_requests"));
+    assert!(rendered.contains("service_name=\"test-service\""));
+}