fix(sdmx_series_ecb_fvc): refresh content digest after key strip

sdmx_series_ecb_fvc/meta.json

@@ -57,8 +57,8 @@
   "build": {
     "built_at": "2026-06-18T22:31:10.537313Z",
     "parsimony_version": null,
-    "builder": null,
-    "content_sha256": "b21ddfb8a2b74fbd9d933309b0550a7f9416a37967966e657edbe352d24a04ea",
+    "builder": "strip-ecb-flow-prefix-keys",
+    "content_sha256": "43305043a26a11a1532620b4792d84530d52ec66643db1338166848704e9fef9",
     "manifest_contract_sha256": "45055cf4058c30d74dbf5fe5d4df3f1564ab82f46a77d244585e5e1ce2dbae3e"
   }
 }