feat: add LATEST_VERSION config for client update detection

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cloud_backend/.env.example

@@ -12,3 +12,6 @@ ACCESS_TOKEN_EXPIRE_MINUTES=60
 # Default sysadmin credentials (created on first startup if admin table is empty)
 ADMIN_USERNAME=sysadmin
 ADMIN_PASSWORD=changeme
+
+# The current latest release version — clients compare against this to detect updates
+LATEST_VERSION=0.0.0

cloud_backend/config.py

@@ -10,6 +10,7 @@ class Settings(BaseSettings):
     ACCESS_TOKEN_EXPIRE_MINUTES: int = 60
     ADMIN_USERNAME: str = "sysadmin"
     ADMIN_PASSWORD: str = "changeme"
+    LATEST_VERSION: str = "0.0.0"
 
     model_config = {"env_file": str(_HERE / ".env")}