nub package manager auto-detected; null observability error fixed

Minor Changes

• #14595 2b390d7 Thanks @colinhacks! - Recognise nub as a package manager

  wrangler now detects nub — from its npm_config_user_agent and an installed nub binary — and autoconfig detects nub projects by their nub.lock, alongside npm, pnpm, yarn, and bun.

Patch Changes

• #14746 a6c214f Thanks @samarth70! - Return a clear error when observability is set to null

  validateObservability guarded only against undefined, so a null value (valid in JSON/JSONC config) passed the typeof value === "object" check and then threw TypeError: Cannot read properties of null (reading 'enabled') while validating the config. It now rejects null with the same "observability" should be an object but got null. diagnostic that the sibling cache validator already produces.