feat(tui): replace Textual with a Go/Bubble Tea interface (#941)

strix/interface/tui/internal/protocol/protocol_test.go

@@ -0,0 +1,22 @@
+package protocol
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestProtocolVersionAndCapabilities(t *testing.T) {
+	if Version != 3 {
+		t.Fatalf("protocol version = %d, want 3", Version)
+	}
+	wantCapabilities := []string{
+		"state-revisions",
+		"collection-deltas",
+		"structured-command-errors",
+		"agents-collection",
+	}
+	if !reflect.DeepEqual(Capabilities, wantCapabilities) {
+		t.Fatalf("capabilities = %#v, want %#v", Capabilities, wantCapabilities)
+	}
+
+}