Adds a business-facing OmniClaw seller example under examples/business-compute/.

[Abiorh001]

What this introduces:

• a real business web app seller surface, not a CLI seller surface
• paid compute products
• paid compute sessions with credits
• paid research-paper PDF products
• direct OmniClaw seller backend integration for x402 requirements and verification
• Redis-backed persistence for business state

What is now supported:

• unpaid access returns 402 Payment Required
• buyer agent pays the business URL through OmniClaw
• seller unlocks only after verification/settlement
• compute returns real computed output
• paper purchase returns a signed download URL
• direct unauthenticated PDF download is blocked
• session creation and session job execution work
• sessions, job history, settlements, metrics, and event logs survive business app restarts

Files added:

• examples/business-compute/app.py
• examples/business-compute/README.md
• examples/business-compute/papers/
• scripts/start_business_compute_demo.sh

Verified end to end:

• direct compute purchase
• paid paper unlock + protected PDF download
• compute session purchase
• session job execution with credit decrement
• Redis-backed restart persistence