Realign Microsoft plugin skills with connector updates

[spasumar-oai]

Summary

Realign the restored specialist Microsoft plugin skills with the latest Microsoft connector contracts. This intentionally keeps the existing specialist plugin boundaries: outlook-email, outlook-calendar, sharepoint, and teams.

Changes

• Update SharePoint guidance for the browse/search contract from openai/openai#798484
  • keyword discovery uses search(query="...")
  • site/folder browse uses search(query=None, hostname=..., site_path=..., folder_path=...)
  • site-scoped discovery uses get_site plus list_site_drives
• Add sharepoint-site-discovery for resolving SharePoint sites, libraries, and folders before file work
• Add outlook-email-shared-mailboxes for delegated/shared mailbox reads, moves, read-state changes, and send_email_on_behalf
• Add outlook-calendar-shared-calendars for delegated/shared calendar writes from openai/openai#807781
• Update Outlook Email and Outlook Calendar umbrella skills to route shared mailbox/calendar work to those specialist workflows
• Update Teams Planner framing so Planner is described as shared Microsoft task infrastructure surfaced through Teams workflows
• Add explicit Planner handoffs from Teams digest, triage, reply-drafting, and umbrella guidance
• Do not add unified outlook or microsoft-365-enterprise plugin bundles; contacts and cross-surface Enterprise workflows remain outside the current restored specialist plugin pack
• Do not change marketplace policy or add new marketplace entries

Testing

• Fetched openai/openai origin/master and confirmed no Microsoft connector implementation changes between local connector analysis and latest fetched remote master
• Verified plugin-to-connector IDs for outlook-email, outlook-calendar, sharepoint, and teams
• Verified no unified Outlook / Microsoft 365 Enterprise plugin IDs or plugin names remain in the plugin tree
• Verified shared mailbox/calendar action names from openai/openai#807781 are covered in specialist Outlook skills
• Verified SharePoint skills document the browse/search contract from openai/openai#798484
• Parsed marketplace JSON during verification
• Parsed updated agents/openai.yaml metadata during verification
• Ran git diff --check origin/main...HEAD