feat(example): add supply-chain-vsm composition demo (S3.5)

Demonstrates infospace composition: the Wealth of Nations infospace is
used as a discipline, applying Smith's economic framework as a lens to
analyse modern supply chain management concepts.

New example: examples/supply-chain-vsm/
- infospace.yaml binding WoN as discipline (../infospace-with-history)
- 3 source documents: coordination mechanisms, capital & inventory,
  market structure (~400 words each, original content)
- supply-chain-entity-schema-v1.0.md with WoN Concept required section
- won-mapping-schema-v1.0.md with Conceptual Continuity rating
- artifacts/won-reference/core-entities.md — 12 curated WoN entities
  for injection as discipline context
- 8 hand-crafted entity files demonstrating LLM output format
- 3 mapping files with full rationale and VSM inheritance chains
- Viable: YES (5/5 thresholds)

Key mappings demonstrated:
  Demand Signal          → Effectual Demand        (Strong, S2)
  Vendor-Managed Inventory → Division of Labour    (Strong, S1/S2)
  Just-in-Time Inventory → Circulating Capital     (Strong, S1/S3)
  Bullwhip Effect        → Natural Price           (Moderate, S2)
  Platform Intermediary  → Merchant Capital        (Strong, S2/S4)
  Monopsony Power        → Combination of Masters  (Strong, S3*)

Platform fix: entity_parser.py now recognises ## Supply Chain Domain
as a domain alias for ## Economic Domain, enabling composed infospaces
to use their own domain section name.

Tutorial §13 rewritten with real commands, real output, and the full
mapping table from the demo.

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

markitect/infospace/entity_parser.py

@@ -120,7 +120,7 @@ def parse_entity_file(path: Path) -> EntityMeta:
     definition = _get_section_text("definition")
     source_chapter = _get_section_text("source_chapter")
     context = _get_section_text("context")
-    domain = _get_section_text("economic_domain")
+    domain = _get_section_text("economic_domain") or _get_section_text("supply_chain_domain")
     original_wording = _get_section_text("smith_s_original_wording")
     modern_interpretation = _get_section_text("modern_interpretation")