feat(core-analytics): scaffold @repo/core-analytics via generator

Add the `pnpm turbo gen core-package analytics` generator template and
run it to scaffold the @repo/core-analytics workspace package. The
package lands in placeholder state (empty barrel export) ready for the
IAnalytics + NoopAnalytics implementation in the next commit.

Includes:
- turbo/generators/templates/core-package/analytics/ templates
- turbo/generators/config.ts analytics generator registration
- packages/core-analytics/ placeholder scaffold
- apps/web-next/next.config.mjs transpilePackages entry

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

apps/web-next/next.config.mjs

@@ -5,6 +5,7 @@ const nextConfig = {
   transpilePackages: [
     "@repo/auth",
     "@repo/blog",
+    "@repo/core-analytics",
     "@repo/core-api",
     "@repo/core-audit",
     "@repo/core-cms",