Add LearnHouse Deployment Isolation Toolkit and debugging tools

- Introduced comprehensive documentation for diagnosing and fixing deployment isolation issues between DEV and LIVE instances.
- Implemented enhanced debug API endpoints for deployment verification, URL hardcoding detection, cookie isolation testing, and session configuration checks.
- Created scripts for visual demonstration of cookie isolation, enhanced debugging deployment, and verification of NextAuth cookie isolation.
- Developed a master isolation verification script to run all isolation checks in sequence and summarize results.
- Added detailed README and environment variable guidelines for proper deployment isolation.

apps/web/app/auth/options.ts

@@ -67,8 +67,8 @@ export const nextAuthOptions = {
         httpOnly: true,
         sameSite: 'lax',
         path: '/',
-        // When working on localhost, the cookie domain must be omitted entirely (https://stackoverflow.com/a/1188145)
-        domain: `.${LEARNHOUSE_TOP_DOMAIN}`,
+        // When working on localhost or with different domains, use the current domain instead of a shared top domain
+        domain: process.env.LEARNHOUSE_COOKIE_DOMAIN || (LEARNHOUSE_TOP_DOMAIN === 'localhost' ? undefined : `.${LEARNHOUSE_TOP_DOMAIN}`),
         secure: !isDevEnv,
       },
     },