docs: restore full strategy depth; add UC-01 and UC-02

- Expand CANONICAL_STRATEGY with retrieval substrates, commerce chairs,
  multi-path discovery, ingestion, quality/decommission, trust bar
- Rebalance platform vs SSP (portal is activation, not the company)
- Add principal-PM use cases for endpoint auto repair and tourism board
- Update product docs and README entry points

docs/product/intermediate.md

@@ -1,15 +1,16 @@
 # Intermediate product (tourism, chambers, visitor bureaus)
 
-Model 2: destinations and membership organizations as discovery nodes.
+Model 2: destinations and membership organizations as discovery and evaluation nodes.
 
 ## Intent
 
-One intermediate relationship should bring many member endpoints online. Boards get an aggregating MCP, member onboarding (via SSP patterns), and a simple dashboard of hits and category demand. Funding often sits in lodging-tax or destination marketing budgets.
+Today, assistants often treat these sites as low-signal link lists. We upgrade them into structured intermediate MCPs backed by live member endpoints. One intermediate relationship should bring many members online and create a funding path through lodging-tax or destination-promotion budgets.
 
-## Detail source
+## Spec source of truth
 
-[Canonical Strategy](../strategy/CANONICAL_STRATEGY.md) (§4 Model 2, §7 GTM wedge).
+- Narrative: [Canonical Strategy](../strategy/CANONICAL_STRATEGY.md) (Model 2 + GTM wedge)  
+- Operating use case: [UC-02](./use-cases/uc-02-intermediate-tourism-board.md)
 
 ## Build status
 
-Not implemented. Engineering Priority 1 after Model 1 spine is real.
+Not implemented. Priority 1 after Model 1 endpoint activation works for a real cohort.