ethereum: bump prysm v7.1.4 → v7.1.6 on mainnet only

Update Prysm beacon-chain image default for ethereum mainnet profiles
(geth pruned/minimal + reth trace); sepolia and hoodi remain on v7.1.4.

Co-authored-by: Cursor <cursoragent@cursor.com>

compose_registry.json

@@ -7563,7 +7563,7 @@
       "trace"
     ],
     "network": "hashkeychain",
-    "node": "node",
+    "node": "kona",
     "relay": null,
     "stack": "op",
     "type": "pruned",
@@ -7579,7 +7579,7 @@
       "trace"
     ],
     "network": "hashkeychain",
-    "node": "node",
+    "node": "kona",
     "relay": null,
     "stack": "op",
     "type": "pruned",