feat: add Value.Hash O(1) change detection before Value.Equal in reconciler

Adds hash field to Fiber<I> for caching FNV-1a hash after each commit.
Hash comparison runs before Value.Equal in reconcileProps for fast bail-out
on unchanged subtrees. Hashes computed during commit phase only (outside
reactive computations) via commitHashes after commitEffects.

src/host/config.ts

@@ -74,6 +74,7 @@ export function createRoot<TTag extends string, Instance, RootCtx>(
         prevProps: null,
         cachedNode: node,
         disposed: false,
+        hash: null,
       };
       if (parentFiber) parentFiber.children.push(fiber);
       return fiber;
@@ -112,6 +113,7 @@ export function createRoot<TTag extends string, Instance, RootCtx>(
       prevProps: null,
       cachedNode: node,
       disposed: false,
+      hash: null,
     };
 
     for (const child of el.children) {
@@ -140,6 +142,7 @@ export function createRoot<TTag extends string, Instance, RootCtx>(
         prevProps: null,
         cachedNode: node,
         disposed: false,
+        hash: null,
       };
     }
 
@@ -168,6 +171,7 @@ export function createRoot<TTag extends string, Instance, RootCtx>(
       prevProps: null,
       cachedNode: node,
       disposed: false,
+      hash: null,
     };
 
     for (const child of el.children) {
@@ -293,6 +297,7 @@ export function createRoot<TTag extends string, Instance, RootCtx>(
         prevProps: null,
         cachedNode: null,
         disposed: false,
+        hash: null,
       };
       const payloadChildren = isURoot(node) ? (node as URoot).children : [node];
       for (const child of payloadChildren) {