fix(sdmx_series_ecb_exr): strip flow-id prefix from series keys

sdmx_series_ecb_exr/meta.json

@@ -36,8 +36,8 @@
   "build": {
     "built_at": "2026-06-18T22:30:48.419206Z",
     "parsimony_version": null,
-    "builder": null,
-    "content_sha256": "8958ecd74a7d2e20aded1eff82ca1ec8d184c304abd018cde452c6b7ef3b78a0",
+    "builder": "strip-ecb-flow-prefix-keys",
+    "content_sha256": "a292a423d426c0b46828ab39dc2baa187e0beecbf67409cff136d6f2722cd544",
     "manifest_contract_sha256": "0b1ef71b7453f31e11d73c8c7761448b3ce6de8cfa11a602339ad72b78a4c476"
   }
 }

sdmx_series_ecb_exr/series.parquet

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:5ebb7fbd0ad6b3807b293f5f24e9f8b256ebf8dc9fab4344c18e4da115b3d79b
-size 61678
+oid sha256:127418f11d6c05f621fd5a5174b365d5acd10364190f2e92cb4db09af4d4a846
+size 118680