feat(vessels): a selected vessel shows its Open Vessel Photos photo and MMSI

Selecting a vessel asks Open Vessel Photos (a free, keyless API) for its
photo by MMSI, once per MMSI. The CONTACTS view shows it under the vessel's
name and MMSI with the photographer, the photo's open licence and a link to
the vessel's page; only images on Open Vessel Photos' own host are shown, and
an answer about another MMSI is no photo. The vessel source exposes the lookup
as getEnrichment({kind: 'photo'}) and fetchOpenVesselPhoto for applications
with their own vessel source.

src/i18n/locales/de.json

@@ -3480,6 +3480,8 @@
   "(+{minutes} min late)": "(+{minutes} min Verspätung)",
   "Exit cockpit to fly to a train": "Cockpit verlassen, um zu einem Zug zu fliegen",
   "Photo © {photographer}": "Foto © {photographer}",
+  "Photo: {photographer} · {licence}": "Foto: {photographer} · {licence}",
+  "Photo · {licence}": "Foto · {licence}",
   "The shared flight isn't reporting now — showing where it was last seen": "Der geteilte Flug sendet gerade nicht – letzte bekannte Position wird gezeigt",
   "The shared flight isn't reporting now — showing where it was at {time}": "Der geteilte Flug sendet gerade nicht – Position um {time} wird gezeigt",
   "The shared military flight isn't reporting now — showing where it was last seen": "Der geteilte Militärflug sendet gerade nicht – letzte bekannte Position wird gezeigt",