Add Paragon integration docs and update agent memory

[mintlify]

Summary

Documents new Paragon-powered integrations from poly_core and updates agent memory docs to reflect custom identifier support.

Changes

New integration pages (9 pages)

• Microsoft Teams — Send messages, list chat messages
• Slack — Send messages, list channels
• Google Drive — List files, search folders
• Notion — Search pages, get page by ID
• Microsoft Outlook — Get emails, list calendar events, get user profile
• Microsoft Dynamics 365 — Search contacts, update contacts
• Google Calendar — Full event CRUD, availability checking, contact lookup (12 actions)
• Jira — Full issue management, project/schema discovery (12 actions)
• ServiceNow — Incident and user management with schema discovery (10 actions)

Updated existing pages (3 pages)

• Salesforce — Added Paragon quick-setup section above existing manual API setup
• Zendesk — Added Paragon ticket management section above existing SIP handoff docs
• Google Sheets — Added Paragon quick-setup section above existing service account setup

Navigation and agent memory

• docs.json — Added 4 new nav groups with all new integration pages
• integrations/introduction.mdx — Added all new integrations to overview
• function/classes/agent-memory.mdx — Documented custom memory identifiers (was incorrectly stating "phone number only")