pdf-server: add disableInteract option for distributed deployments

Adds a `disableInteract` boolean to `createServer()` options that skips
registering the `interact`, `poll_pdf_commands`, and `submit_page_data`
tools (all relying on an in-memory command queue). Adjusts `display_pdf`
description and schema accordingly when disabled.

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

Author: ochafik