Previously, features like `XMPP_FEATURE_OMEMO_DEVICELIST_NOTIFY` were
added in separate init methods (e.g., `omemo_devicelist_subscribe`) via
`caps_add_feature`, triggering `cl_ev_presence_send` and sending multiple
"online" XMPP presence stanzas. This caused other clients to see users
as appearing "online" multiple times.
This change adds `STANZA_NS_MOOD_NOTIFY` and
`XMPP_FEATURE_OMEMO_DEVICELIST_NOTIFY` in `caps_init`, ensuring they are
in `prof_features` early. This allows `caps_add_feature` to exit early
when called for these features, avoiding redundant presence updates.
