implement ota updates

backend/app/config.py

@@ -55,6 +55,30 @@ class EnvSettings(BaseSettings):
         default=True,
         description="Run the Telegram command bot when a token is configured.",
     )
+
+    # ---- Android OTA updates -----------------------------------------------
+    # The Gitea repository is private, so these cannot be read anonymously.
+    # The token is a read-only personal access token; it never leaves the
+    # backend, and the Android client only sees /api/updates/android.
+    gitea_url: str = Field(
+        default="https://git.timka.su",
+        description="Base URL of the Gitea instance that runs the Android workflow.",
+    )
+    gitea_repo: str = Field(
+        default="timka123/kadence",
+        description="owner/repository whose Actions artifacts carry the APK.",
+    )
+    gitea_token: str = Field(
+        default="",
+        description=(
+            "Read-only Gitea token used to read Actions artifacts. Empty disables "
+            "the Android update endpoint."
+        ),
+    )
+    gitea_update_branch: str = Field(
+        default="master",
+        description="Only successful builds from this branch are offered as updates.",
+    )
     api_token: str = Field(
         default="",
         description=(