fix: raise data-manager memory cap to 8g for DELFI-class GTFS feeds

The 4g cap was killing gtfsclean mid-run on the German DELFI feed (the national aggregator that bundles every operator in Germany — ~425 MB raw zip, ~2.2M trips). Measured peaks during cleanup are ~5.5–5.7 GB, well above the 4g ceiling. Bump to 8g, which fits DELFI with comfortable headroom and aligns with osrm's existing footprint. Smaller deployments that don't touch DELFI-class national feeds still get a more generous-than-needed limit but Docker doesn't preallocate, so the only cost is the OOM-killer ceiling moving up.

Author: Medformatik

services/data-manager/service.json

@@ -15,7 +15,7 @@
       "HOST": "0.0.0.0",
       "DATA_MANAGER_AUTH_TOKEN": "${DATA_MANAGER_AUTH_TOKEN:?DATA_MANAGER_AUTH_TOKEN must be set — generate with: openssl rand -hex 32}"
     },
-    "memory": "4g",
+    "memory": "8g",
     "restart": "unless-stopped",
     "healthcheck": {
       "type": "http",