feat(06-01): grow router verbs, factories, and guard registry

- Add Post/Put/Patch/Delete on pact.Router and surf Router/Group
- Resolve name:param middleware via RegisterMiddlewareFactory
- Add bouncer.Registry with Guard, CredentialGuard, UnauthorizedWriter
- Re-express jwt as NewJWTGuard without changing Middleware bodies

bouncer/context_test.go

@@ -0,0 +1,21 @@
+package bouncer
+
+import "testing"
+
+func TestContextCredentialRoundTrip(t *testing.T) {
+	if _, ok := Credential(t.Context()); ok {
+		t.Fatal("empty context must have no credential")
+	}
+	if _, ok := Credential(nil); ok {
+		t.Fatal("nil context must have no credential")
+	}
+	token := &struct{ Name string }{Name: "parity"}
+	got, ok := Credential(WithCredential(t.Context(), token))
+	if !ok || got != token {
+		t.Fatalf("got %#v ok=%t", got, ok)
+	}
+	got, ok = Credential(WithCredential(nil, token))
+	if !ok || got != token {
+		t.Fatalf("nil ctx got %#v ok=%t", got, ok)
+	}
+}