Enhance API path normalization and configuration validation

- Introduced a new function to normalize request URL paths, collapsing duplicate slashes and clearing raw paths to ensure correct routing in the reverse proxy.
- Updated the gateway to utilize the normalization function for API requests, improving routing consistency.
- Trimmed whitespace from server configuration fields in the validation process to prevent potential issues with malformed URLs.
- Enhanced documentation in GATEWAY_RUN.md to clarify the importance of proper URL formatting and configuration.

internal/proxy/reverse_test.go

@@ -25,6 +25,32 @@ func (c *captureTransport) RoundTrip(req *http.Request) (*http.Response, error)
 	}, nil
 }
 
+func TestDirectorDoubleSlashPathMatchesStripPrefix(t *testing.T) {
+	target, err := url.Parse("http://127.0.0.1:9")
+	if err != nil {
+		t.Fatal(err)
+	}
+	cap := &captureTransport{}
+	rp := NewReverseProxy(target, "/api/mtg", "/v1", "")
+	rp.Transport = cap
+
+	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, "http://127.0.0.1:9/", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	req.URL.Path = "/api//mtg/health"
+	rp.ServeHTTP(httptest.NewRecorder(), req)
+
+	if cap.got == nil {
+		t.Fatal("no outgoing request captured")
+	}
+	want, err := url.Parse("http://127.0.0.1:9/v1/health")
+	if err != nil {
+		t.Fatal(err)
+	}
+	assertSameURL(t, cap.got.URL, want)
+}
+
 func TestDirectorRewritesPath(t *testing.T) {
 	target, err := url.Parse("http://127.0.0.1:9")
 	if err != nil {