Add open source alternative to Pocus / Common Room: Beton Inspector

Following the template in CONTRIBUTING_TO_OSB.md (adding an open-source alternative). Happy to submit via the GraphQL flow if you can share a session, otherwise flagging here for inclusion.

**Add open source alternative to Pocus / Common Room:**
- Name: Beton Inspector
- Repository: https://github.com/getbeton/inspector
- Website: https://getbeton.ai
- Description: Open-source revenue intelligence — detects buying signals from PostHog product-usage data + CRM, scores accounts, and routes the warmest leads to sales reps. Self-hostable via Docker.
- License: AGPL-3.0
- Category: CRM & Sales / Revenue Intelligence
- Notes: Open-source alternative to the product-led-sales signal platforms Pocus and Common Room. Built with TypeScript (Next.js, Supabase/PostgreSQL).

Thanks for maintaining the directory!