fix(example): standardise domain enum and source chapter format in schema/rules

Two root causes of metric fragmentation observed in collection checks:

1. Schema's Economic Domain used free-form examples ("labour economics,
   trade theory") which overrode the enum in extraction-rules.md, causing
   the LLM to produce multi-domain strings and non-canonical values.
   Fix: schema now specifies the exact 7-value enum with descriptions.

2. Source Chapter had no format constraint, producing 9 different formats
   for 7 chapters (full titles, mixed Roman/Arabic numerals, asterisks).
   Fix: extraction-rules now mandate "Book [Roman], Chapter [n]" exactly.

These fixes are prerequisites for clean reprocessing (S3.2 continuation).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

examples/infospace-with-history/artifacts/guidelines/extraction-rules.md

@@ -57,5 +57,10 @@ entities at the level of specificity where they carry independent meaning.
 - Each entity must have a definition that would be comprehensible without
   reading the source chapter.
 - Each entity must cite the specific book and chapter of first appearance.
-- Economic Domain must be one of: Production, Distribution, Exchange,
-  Consumption, Accumulation, Regulation, or General Theory.
+- **Economic Domain** must be EXACTLY ONE of: Production, Distribution,
+  Exchange, Consumption, Accumulation, Regulation, or General Theory.
+  Do not combine multiple domains. Do not use any other value.
+- **Source Chapter format**: Use `Book [Roman numeral], Chapter [number]`
+  — for example `Book I, Chapter 3`. Do not include the chapter title,
+  quotation marks, markdown formatting, or asterisks. Use Roman numerals
+  for the book (I, II, III, IV, V).