add cache metadata

data/sft_t2t_books81_joint_mode2_bpe6400.json

@@ -0,0 +1,25 @@
+{
+  "input_sft": "data/sft_t2t.paragraphs.feather",
+  "manifest": "BiAttn/runs/minimind_16m_books81_manifest.txt",
+  "books": 81,
+  "tokenizer": "data/minimind/generated/pretrain_t2t_mini.bytes_bpe6400.tokenizer.json",
+  "vocab_size": 6400,
+  "chapter_separator_id": 3,
+  "workers": 8,
+  "batch_size": 2048,
+  "max_block_chars": 4096,
+  "pack_shift": 512,
+  "seed": 20260921,
+  "splits": {
+    "train": {
+      "blocks": 1664999,
+      "chars": 6562520515,
+      "tokens": 3491533896
+    },
+    "dev": {
+      "blocks": 166,
+      "chars": 657484,
+      "tokens": 615426
+    }
+  }
+}