Let the Android head finish signing in against the development realm

The head redirects to dev.dodotech.dodossh:/callback — a private-use scheme, RFC 8252 §7.1, matching the
intent filter on MainActivity — and this realm listed only the desktop's loopback. So a sign-in started
from a phone reached Keycloak and was refused there, with invalid_redirect_uri and nothing wrong on the
phone at all. The realm simply had never been told the second head exists.

Found by running the head against a local stack rather than by reading it: the desktop's own sign-in has
always worked here, which is exactly why this went unnoticed.

Note for anyone picking the change up: --import-realm skips a realm that already exists, so a restart does
nothing and the old configuration goes on being served. The container has to be recreated. The steps are in
the comment on the keycloak service in docker-compose.dev.yml.

deploy/keycloak/realm-dodossh.json

@@ -26,7 +26,8 @@
         "post.logout.redirect.uris": "http://127.0.0.1/*"
       },
       "redirectUris": [
-        "http://127.0.0.1/callback"
+        "http://127.0.0.1/callback",
+        "dev.dodotech.dodossh:/callback"
       ],
       "webOrigins": [],
       "protocolMappers": [