docs(site): show packet-backed agent requests - #316

Summary

• update the main website hero copy to reference toAgentRequest()
• update the How it works AI-boundary example to show packet-backed selected sources
• update integrations copy to describe the JSON-ready request payload

Tests

• opened http://127.0.0.1:4187 locally in browser
• Playwright content check for toAgentRequest, selectionFromPacket, and sources: ['accounts']
• screenshot captured at /tmp/askable-site-agent-request.png
• git diff --check