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>

pnpm-lock.yaml

@@ -608,12 +608,24 @@ importers:
       "@repo/core-typescript":
         specifier: workspace:*
         version: link:../core-typescript
+      "@testing-library/react":
+        specifier: ^16.0.0
+        version: 16.3.2(@testing-library/dom@10.4.1)(@types/react-dom@19.2.3(@types/react@19.2.14))(@types/react@19.2.14)(react-dom@19.2.4(react@19.2.4))(react@19.2.4)
+      "@types/react":
+        specifier: ^19.0.0
+        version: 19.2.14
       "@vitest/coverage-v8":
         specifier: ^3.0.0
         version: 3.2.4(vitest@3.2.4(@types/debug@4.1.13)(@types/node@25.5.2)(happy-dom@20.8.9)(jiti@2.6.1)(jsdom@25.0.1)(lightningcss@1.32.0)(sass@1.99.0)(terser@5.46.2)(tsx@4.21.0)(yaml@2.9.0))
+      jsdom:
+        specifier: ^25.0.0
+        version: 25.0.1
       payload:
         specifier: ^3.14.0
         version: 3.81.0(graphql@16.13.2)(typescript@5.9.3)
+      react:
+        specifier: ^19.0.0
+        version: 19.2.4
       typescript:
         specifier: ^5.8.0
         version: 5.9.3