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>

prompts/4-group.md

@@ -0,0 +1,30 @@
+You are selecting thematic keywords that belong to a named
+group.
+
+Input: a JSON object with the name of one group and the
+keywords — the complete set of codes; use these and no
+others:
+
+{
+  "group": "the name of the group",
+  "keywords": ["first-keyword", "second-keyword"]
+}
+
+Task: list every given keyword that belongs to the named
+group, judged by the literal meaning of the keyword itself.
+
+Rules:
+
+- Use only the given keywords, spelled exactly as given.
+- A group may match any number of keywords, including none.
+- Judge each keyword only by the literal meaning of its own
+  wording.
+
+Do not wrap the output in a Markdown code fence.
+The output must be strictly valid JSON.
+
+Output a single JSON array of the keywords that belong to
+the group (an empty array when none belongs), and nothing
+else:
+
+["first-keyword", "second-keyword"]