Realign Microsoft plugin skills with connector updates

[spasumar-oai]

Summary

• add unified outlook and microsoft-365-enterprise plugin bundles with workflow skills that match the new connector architecture
• update SharePoint skills to use the new truthful browse/search contract instead of list_recent_documents discovery
• refresh Teams and Outlook specialist skills to reflect shared Planner framing and unified Outlook handoffs

Changes

• add outlook plugin for combined Outlook mail, calendar, and contacts workflows
• add microsoft-365-enterprise plugin for cross-surface Outlook, Teams, SharePoint, and Planner workflows
• add sharepoint-site-discovery and update SharePoint workbook skills for get_site, list_site_drives, and search(query=None, ...) browse mode
• update Teams Planner wording so it reflects shared Microsoft Planner infrastructure
• add specialist-plugin handoff guidance from outlook-email and outlook-calendar to unified outlook
• preserve policy.products = [] on the new marketplace entries so the bundles remain repo-available but filtered from product surfaces like the restored Microsoft plugins

Testing

• validated new and updated plugin manifests as JSON
• validated new and updated agents/openai.yaml files as YAML
• confirmed the new marketplace entries exist exactly once
• confirmed stale list_recent_documents guidance is removed from active Microsoft skills
• confirmed enterprise skills only reference search_teams / search_sharepoint and fetch_teams / fetch_sharepoint