fix: default DEM URL to api.open-elevation.com

No configuration needed out of the box; --dem-url only required to
override the default with a self-hosted or alternative endpoint.

bincio/serve/cli.py

@@ -21,7 +21,7 @@ console = Console()
 @click.option("--max-users", default=None, type=int, help="Override max users for this instance (0 = unlimited; updates the DB setting)")
 @click.option("--public-url", default=None, envvar="PUBLIC_URL", help="Public base URL (e.g. https://yourdomain.com). Required for Strava OAuth to work behind a reverse proxy.")
 @click.option("--webroot", default=None, type=click.Path(), help="Nginx webroot (e.g. /var/www/bincio). When set, uploads trigger a full Astro build + rsync so new activity pages are immediately accessible without a git push.")
-@click.option("--dem-url", default=None, envvar="DEM_URL", help="Base URL of an Open-Elevation-compatible API (enables 'Recalculate elevation' button in the edit drawer).")
+@click.option("--dem-url", default=None, envvar="DEM_URL", help="Base URL of an Open-Elevation-compatible API (default: https://api.open-elevation.com).")
 def serve(data_dir: str, site_dir: Optional[str], host: str, port: int,
           strava_client_id: Optional[str], strava_client_secret: Optional[str],
           max_users: Optional[int], public_url: Optional[str],
@@ -77,8 +77,7 @@ def serve(data_dir: str, site_dir: Optional[str], host: str, port: int,
         console.print(f"  Users: [yellow]max {current_limit}[/yellow]")
     else:
         console.print(f"  Users: [dim]unlimited[/dim]")
-    if dem_url:
-        console.print(f"  DEM:   [cyan]{dem_url}[/cyan]")
+    console.print(f"  DEM:   [cyan]{srv.dem_url}[/cyan]")
     console.print()
 
     log_config = uvicorn.config.LOGGING_CONFIG.copy()