test: check request errors and stop asserting PathRewrite on /v1/models

/v1/models is served from config by ServeHTTP (task 2.5) so it never reaches
routing; the rewrite test now uses a non-reserved path.

internal/proxy/proxy_test.go

@@ -105,7 +105,9 @@ func TestProxyPathRewrite(t *testing.T) {
 	server := httptest.NewServer(handler)
 	defer server.Close()
 
-	resp, err := http.Get(server.URL + "/v1/models")
+	// Not /v1/models: ServeHTTP serves that endpoint from config (task 2.5)
+	// and returns before routing, so it never exercises PathRewrite.
+	resp, err := http.Get(server.URL + "/some/path")
 	if err != nil {
 		t.Fatalf("request failed: %v", err)
 	}
@@ -146,7 +148,7 @@ func TestProxyConnectionReuse(t *testing.T) {
 	defer handler.Close()
 
 	// Verify connection reuse by checking that the same transport is used
-	
+
 	// We can't easily count raw TCP connections in this test setup,
 	// but we can verify that the transport is being reused by checking
 	// that the same transport handles both requests
@@ -402,7 +404,10 @@ func TestProxyPreservesBody(t *testing.T) {
 	defer server.Close()
 
 	testBody := `{"model": "test", "messages": []}`
-	resp, _ := http.Post(server.URL+"/test", "application/json", strings.NewReader(testBody))
+	resp, err := http.Post(server.URL+"/test", "application/json", strings.NewReader(testBody))
+	if err != nil {
+		t.Fatalf("request failed: %v", err)
+	}
 	resp.Body.Close()
 
 	if receivedBody != testBody {