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

sdmx_series_ecb_fm/meta.json

@@ -42,8 +42,8 @@
   "build": {
     "built_at": "2026-06-18T22:30:56.847438Z",
     "parsimony_version": null,
-    "builder": null,
-    "content_sha256": "9823117bdd16b062576c2b1621fa17bff2a1a8e0b4eef4647eac0801f2bc6d18",
+    "builder": "strip-ecb-flow-prefix-keys",
+    "content_sha256": "c90f1ba48c48d9cbc47bf95cbe677c8bd4655f085bdaf02a50a2c81a2c54861e",
     "manifest_contract_sha256": "a700f0c1f76dcae5464e82c2e6181f7c8f6a546fb3dbb6370cbb0d3547fcda4b"
   }
 }

sdmx_series_ecb_fm/series.parquet

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:eb511be959055da69e541a0078ecd29430d63908c506d61dea11d1385dffd984
-size 11368
+oid sha256:a04f5d891688cdd7742dd0473efccb40830e38acaad4a5f1ac948f37123b2802
+size 13112