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>

examples/supply-chain-vsm/output/entities/platform-intermediary.md

@@ -0,0 +1,50 @@
+<!-- generated: provider=openrouter model=arcee-ai/trinity-large-preview:free date=2026-02-22 source=market-structure -->
+
+# Platform Intermediary
+
+## Definition
+
+A company that controls the infrastructure through which supply chain
+participants transact, without itself producing or consuming goods. Platform
+intermediaries earn revenue from network access fees, transaction commissions,
+data analytics, and financing services. Their market power derives from
+network effects: value accrues to participants proportionally to the size
+of the network, creating winner-take-most dynamics. Unlike traditional
+intermediaries, platforms bear no inventory risk — that remains with
+producers and carriers.
+
+## Source
+
+Market Structure in Modern Supply Chains, §Platform Intermediaries
+
+## Supply Chain Domain
+
+Market Structure
+
+## VSM Assignment
+
+S4 — Platform intermediaries function as the intelligence layer of the
+supply chain, aggregating and intermediating market information across many
+buyers and sellers simultaneously. They are not operational (S1) but shape
+what operations are possible and at what price.
+
+## WoN Concept
+
+Merchant Capital — Smith's analysis of merchant capital — capital employed
+to buy in one market and sell in another, earning profit from differential
+access — maps closely to platform intermediaries. Both earn profit not
+from production but from controlling access to exchange. Smith noted that
+merchants are geographically mobile and have no necessary loyalty to any
+particular productive system, giving them structural leverage over producers
+who are fixed. Platform intermediaries exhibit the same dynamic at
+unprecedented scale: the platform has no physical attachment, yet producers
+who exit lose access to the entire buyer network.
+
+## Modern Context
+
+Platform intermediaries represent a structural innovation Smith could not
+have anticipated: they capture the coordination function of merchant capital
+while eliminating its inventory risk and capital requirements. The result is
+a higher-leverage, lower-capital form of intermediation than Smith described,
+but the underlying logic — control of the exchange infrastructure creates
+extractable surplus — is precisely what he analysed.