chore(config): make immich api key optional in compose

The environment variable handling for IMMICH_API_KEY has been updated to remove strict requirement checks. This change improves setup flexibility by allowing services to start even if the API key is not explicitly defined in the .env file, assuming a default or alternative mechanism handles missing values gracefully.

- Removes mandatory check for IMMICH_API_KEY environment variable

compose.yaml

@@ -7,7 +7,7 @@ services:
     restart: "no"
     environment:
       IMMICH_URL: ${IMMICH_URL:?Set IMMICH_URL in .env}
-      IMMICH_API_KEY: ${IMMICH_API_KEY:?Set IMMICH_API_KEY in .env}
+      IMMICH_API_KEY: ${IMMICH_API_KEY}
       IMMICH_LIBRARY_ID: ${IMMICH_LIBRARY_ID:?Set IMMICH_LIBRARY_ID in .env}
       EXTERNAL_ROOT: ${EXTERNAL_ROOT:-/mnt/nextcloud-photos}
       ALBUM_MODE: ${ALBUM_MODE:-root}