Renumber the pipeline substeps to match the paper (5-1 becomes 5a)

prompts/ and runs/ move by git mv; zero padding dropped; the
arbitration and LLM-merge rows in the cost ledger carry no new
name -- their step column reads 已廢棄 with the original name
kept in a new last column.  Archived meta.json files and past
decision-log entries keep the names they were written with.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

runs/4-group/run3/meta.json

@@ -0,0 +1,25 @@
+{
+  "script_version": "run_llm.py 3.1.0",
+  "model": "claude-fable-5",
+  "temperature": null,
+  "thinking": null,
+  "max_tokens": 8192,
+  "prompt_path": "../prompts/04-group.md",
+  "prompt_sha256": "50e1d5d6c4115d090ae4ab1e801ea74db0b2dcdd47213ce0feb6749e034a41e9",
+  "input_path": "instance/llm-input-group.jsonl",
+  "input_sha256": "7fd97ae165270cb91461aedf411050892667b928d8584fceffea6f9649e003c7",
+  "item_count": 4,
+  "dry_run": false,
+  "started_at": "2026-08-14T23:39:37+08:00",
+  "batch": {
+    "batch_id": "msgbatch_01DveEMYyjCAYe6wxpcCD87V",
+    "submitted_at": "2026-08-14T23:39:43+08:00",
+    "ended_at": "2026-08-14T15:41:46.778015+00:00"
+  },
+  "usage": {
+    "cache_creation_input_tokens": 0,
+    "cache_read_input_tokens": 0,
+    "input_tokens": 5553,
+    "output_tokens": 1975
+  }
+}