remove-demo-limits

Remove the managed-template trial restrictions with the smallest coherent change.

Goal

Make the fork behave like a normal self-hosted deployment:

• no trial session cap
• no trial message cap
• no hosted-only restriction errors
• no hosted-demo delete restrictions
• no dead helper code or stale tests

Inspect first

Read these files before editing:

• apps/web/lib/managed-template-trial.ts
• apps/web/app/api/sessions/route.ts
• apps/web/app/api/chat/route.ts
• apps/web/app/api/sessions/[sessionId]/chats/[chatId]/messages/[messageId]/route.ts
• apps/web/app/api/sessions/route.test.ts
• apps/web/app/api/chat/route.test.ts
• apps/web/app/api/sessions/[sessionId]/chats/[chatId]/messages/[messageId]/route.test.ts