feat(web): continue source-backed implementation waves

web/protocol/physics-commands.ts

@@ -0,0 +1,9 @@
+import type { PhysicsSimulationManifestIR } from "./physics-simulation";
+import type { WebEngineEditCommand } from "./web-engine";
+
+/** Typed constructor for bounded physics metadata commits to WebEngine Main. */
+export const physicsCommands = Object.freeze({
+  setManifest(manifest: PhysicsSimulationManifestIR): Extract<WebEngineEditCommand, { type: "setPhysicsSimulation" }> {
+    return { type: "setPhysicsSimulation", manifest };
+  },
+  } as const);