feat: in-app Chat (Matrix JWT SSO) + Drive (embedded oCIS)
- api: matrix-sso module (tuwunel jwt -> login/get_token), POST /matrix/session, GET /matrix/identity, drive controller
- web: /chat full-height Element view, /files Library+Drive tabs, embedded-app frame component
- edge: /hub-sso.html handshake route (origin-pinned CSP), X-Frame-Options strip on files
- oCIS: csp.yaml frame-ancestors app.occupymedia.cc
- server config still required: tuwunel [global.jwt], MATRIX_SSO_JWT_SECRET, oCIS restart