docs: add Outlook (Microsoft 365) integration docs

[jpinho]

Summary

• New Outlook (Microsoft 365) section under Communications with three pages: Overview, Setup, and Security & Privacy.
• Renames the Messaging sidebar label to Communications to cover the broader scope (mail today; Outlook calendar and Teams on the roadmap).
• Adds four SVG diagrams: architecture, connect flow, trust model, data flow.

Impact

• Customers and IT admins now have a single source of truth for the Outlook integration: how it connects, what scopes it asks for, what gets stored where, how access works inside epilot, and how to disconnect or revoke.
• The Security & Privacy page is explicit about the trust boundary (Entra controls what flows in; epilot controls who sees it once in) and uses the SES-parity argument to address concerns about Entra ACLs not being enforced at view time inside epilot.
• The label change from Messaging to Communications avoids confusion with the in-product "Messaging Hub" feature name as the section's scope broadens.

Product Value

• Reduces back-and-forth with Sales Engineering and Support on Outlook setup, scope rationale, and DPA/CISO questions.
• Gives prospects a doc to forward to their security and IT teams without further translation – the Security & Privacy page is structured for exactly that audience.
• Sets clear, public expectations about what is shipped today versus what is on the roadmap, so customer conversations align on scope.