feat(core-analytics): add React provider and useAnalytics hook

Adds a ./react subpath export to @repo/core-analytics containing
<AnalyticsProvider value={IAnalytics}> and useAnalytics(): IAnalytics.
useAnalytics() throws AnalyticsContextError when called outside a provider.
React Testing Library test verifies track() flows through context using
RecordingAnalytics. Switches vitest config to pick up .tsx test files
via environmentMatchGlobs and extends tsconfig to react-library.json
for JSX support.

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

packages/core-analytics/tsconfig.json

@@ -1,5 +1,5 @@
 {
-  "extends": "@repo/core-typescript/base.json",
+  "extends": "@repo/core-typescript/react-library.json",
   "compilerOptions": {
     "outDir": "dist",
     "rootDir": ".",
@@ -7,6 +7,6 @@
       "@/*": ["./src/*"]
     }
   },
-  "include": ["**/*.ts"],
+  "include": ["**/*.ts", "**/*.tsx"],
   "exclude": ["node_modules", "dist"]
 }