feat(core-consent): add ConsentProvider + useConsent() React subpath

Adds the ./react subpath to @repo/core-consent following the same
pattern as @repo/core-analytics/react:

- ConsentProvider wraps IConsent in React context
- useConsent() returns the injected IConsent or throws ConsentContextError
- RTL tests cover context propagation, grant/withdraw delegation,
  isGranted state reflection, getCategories, and missing-provider error
- package.json: ./react export + React optional peerDep + RTL devDeps
- tsconfig: extend react-library.json, include .tsx
- vitest.config: jsdom environment for .test.tsx + jsdom setup

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/core-consent/vitest.config.ts

@@ -1,9 +1,17 @@
 import path from "node:path";
-import { mergeConfig } from "vitest/config";
+import { defineConfig, mergeConfig } from "vitest/config";
 import { nodeVitestConfig } from "@repo/core-typescript/vitest.base.node";
 
-export default mergeConfig(nodeVitestConfig, {
-  resolve: {
-    alias: { "@": path.resolve(__dirname, "./src") },
-  },
-});
+export default mergeConfig(
+  nodeVitestConfig,
+  defineConfig({
+    test: {
+      include: ["src/**/*.test.{ts,tsx}", "tests/**/*.test.{ts,tsx}"],
+      environmentMatchGlobs: [["**/*.test.tsx", "jsdom"]],
+      setupFiles: ["@repo/core-testing/setup/jsdom"],
+    },
+    resolve: {
+      alias: { "@": path.resolve(__dirname, "./src") },
+    },
+  }),
+);