feat: add Value.Equal bail-out check before reconciliation

Add TypeBox Value.Equal deep-comparison as first optimization layer
in reconcileProps. When a fiber's cached node is deep-equal to the
next node, skip prepareUpdate, commitUpdate, and children
reconciliation entirely. New cachedNode field on Fiber stores the
last reconciled node for comparison.

test/fiber.test.ts

@@ -1,6 +1,15 @@
 import { describe, it, expect, expectTypeOf } from "vitest";
 import type { Fiber, Effect } from "../src/host/fiber.js";
 
+const baseFiber: Omit<Fiber<string>, "instance" | "tag" | "props" | "key"> = {
+  children: [],
+  parent: null,
+  effect: null,
+  signalDisposers: [],
+  prevProps: null,
+  cachedNode: null,
+};
+
 describe("Fiber<I> interface", () => {
   it("has all required fields", () => {
     const fiber: Fiber<string> = {
@@ -8,11 +17,7 @@ describe("Fiber<I> interface", () => {
       tag: "div",
       props: { class: "test" },
       key: "a",
-      children: [],
-      parent: null,
-      effect: null,
-      signalDisposers: [],
-      prevProps: null,
+      ...baseFiber,
     };
     expect(fiber.instance).toBe("inst-1");
     expect(fiber.tag).toBe("div");
@@ -23,6 +28,7 @@ describe("Fiber<I> interface", () => {
     expect(fiber.effect).toBeNull();
     expect(fiber.signalDisposers).toEqual([]);
     expect(fiber.prevProps).toBeNull();
+    expect(fiber.cachedNode).toBeNull();
   });
 
   it("supports key as undefined", () => {
@@ -31,11 +37,7 @@ describe("Fiber<I> interface", () => {
       tag: "span",
       props: {},
       key: undefined,
-      children: [],
-      parent: null,
-      effect: null,
-      signalDisposers: [],
-      prevProps: null,
+      ...baseFiber,
     };
     expect(fiber.key).toBeUndefined();
   });
@@ -46,22 +48,15 @@ describe("Fiber<I> interface", () => {
       tag: "div",
       props: {},
       key: undefined,
-      children: [],
-      parent: null,
-      effect: null,
-      signalDisposers: [],
-      prevProps: null,
+      ...baseFiber,
     };
     const child: Fiber<string> = {
       instance: "child-inst",
       tag: "span",
       props: {},
       key: "child-1",
-      children: [],
+      ...baseFiber,
       parent,
-      effect: null,
-      signalDisposers: [],
-      prevProps: null,
     };
     parent.children.push(child);
     expect(child.parent).toBe(parent);
@@ -75,11 +70,8 @@ describe("Fiber<I> interface", () => {
       tag: "div",
       props: {},
       key: undefined,
-      children: [],
-      parent: null,
-      effect: null,
+      ...baseFiber,
       signalDisposers: [() => disposed.push("a"), () => disposed.push("b")],
-      prevProps: null,
     };
     fiber.signalDisposers.forEach((d) => d());
     expect(disposed).toEqual(["a", "b"]);
@@ -104,11 +96,7 @@ describe("Effect<I> union type", () => {
       tag: "span",
       props: {},
       key: undefined,
-      children: [],
-      parent: null,
-      effect: null,
-      signalDisposers: [],
-      prevProps: null,
+      ...baseFiber,
     };
     const effect: Effect<string> = { type: "insert", before };
     expect(effect.type).toBe("insert");
@@ -121,11 +109,7 @@ describe("Effect<I> union type", () => {
       tag: "span",
       props: {},
       key: undefined,
-      children: [],
-      parent: null,
-      effect: null,
-      signalDisposers: [],
-      prevProps: null,
+      ...baseFiber,
     };
     const effect: Effect<string> = { type: "move", before };
     expect(effect.type).toBe("move");
@@ -148,10 +132,8 @@ describe("Effect<I> union type", () => {
       tag: "div",
       props: {},
       key: undefined,
-      children: [],
-      parent: null,
+      ...baseFiber,
       effect: { type: "update", payload: "x" },
-      signalDisposers: [],
       prevProps: {},
     };
     expect(fiber.effect!.type).toBe("update");
@@ -179,11 +161,7 @@ describe("Fiber re-export from barrel", () => {
       tag: "div",
       props: {},
       key: undefined,
-      children: [],
-      parent: null,
-      effect: null,
-      signalDisposers: [],
-      prevProps: null,
+      ...baseFiber,
     };
     const _effect: _EffectCheck = { type: "remove" };
     expect(_fiber.instance).toBe("inst");