feat(01-01): boot hello app and dispatch greeter:hello

- Add party plugin registry with Register-before-Boot activation
- Add backpack, compass, bonfire, and pact capability interfaces
- Add examples/hello with two compiled plugin modules

compass/config_test.go

@@ -0,0 +1,23 @@
+package compass
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLoadStringFromAppSection(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "app.yaml")
+	if err := os.WriteFile(path, []byte("name: hello-app\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	cfg, err := Load(dir)
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	if got := cfg.String("app.name"); got != "hello-app" {
+		t.Fatalf("String(app.name) = %q, want hello-app", got)
+	}
+}