sync_matrix_space() now invites every active member to the rooms in
member_invite_rooms(): MATRIX_INVITE_ROOMS when set, else the co-op Space +
General room; legacy MATRIX_EXTRA_ROOMS is still appended. The set is explicit
configuration, never "every child of the Space", so operator-only rooms are not
pushed at members. Skillshare (!NSPfCdVP7TWTtFoAz1TxVOcqnoDIpMoJDiPb_XS79ys)
was missing from the invite set, so no member who joined after it was created
was ever told about it; including it here makes the nightly sweep self-heal.