implement ota updates

.env.example

@@ -27,6 +27,16 @@ SCHEDULER_ENABLED=true
 TELEGRAM_BOT_ENABLED=true
 LOG_LEVEL=INFO
 
+# ---- Android OTA updates ---------------------------------------------------
+# The repository is private, so the backend reads Actions artifacts on the
+# phone's behalf. Create a read-only token at
+# https://git.timka.su/user/settings/applications and paste it here; without it
+# /api/updates/android answers 503 and the app simply never offers an update.
+GITEA_URL=https://git.timka.su
+GITEA_REPO=timka123/kadence
+GITEA_TOKEN=
+GITEA_UPDATE_BRANCH=master
+
 # ---- web login (closes the browser UI to everyone but you) -----------------
 # Unset: the browser UI is as open as the API ("off by default" above). Set
 # either of these and the login screen appears — the desktop app is untouched,