Belief/Trade reorg: move legacy aux files into metadata

Belief/metadata/split_config_v1_profilegen_llm.json

@@ -0,0 +1,29 @@
+{
+  "version": "v1",
+  "track": "profilegen",
+  "profile_generator": "gpt-5.4",
+  "seed": 20260318,
+  "experiment_wallets_file": "wallet_ids_diverse_nonoverlap_2000_seed20260318.txt",
+  "experiment_wallets": 2000,
+  "split_ratios": {
+    "train": 0.7,
+    "validation": 0.15
+  },
+  "workers": 10,
+  "flush_every_wallets": 200,
+  "counts": {
+    "train": {
+      "samples": 98094,
+      "wallets": 2000
+    },
+    "validation": {
+      "samples": 21147,
+      "wallets": 2000
+    },
+    "test": {
+      "samples": 22204,
+      "wallets": 2000
+    }
+  },
+  "test_source": "outputs/predictions_profilegen_test_gpt-5_4.jsonl"
+}