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>

coverage/summary.json

@@ -1,18 +1,18 @@
 {
-  "generatedAt": "2026-05-19T13:18:49.389Z",
-  "commit": "ae4e0f2",
+  "generatedAt": "2026-05-19T19:19:27.597Z",
+  "commit": "33e3c09",
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@@ -59,17 +59,17 @@
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     "@repo/core-shared": {