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/use-cases/README.md

@@ -1,5 +1,23 @@
 # Use cases
 
-Canonical use cases (Bob’s Garage, destination board, etc.) will land here as structured product specs.
+Canonical use cases for product, engineering, and GTM. These are operating specs, not marketing blurbs.
 
-Until then, narrative examples remain in the strategy and archive; do not treat the archive as the product spec.
+| ID | Name | Model | Status |
+|----|------|-------|--------|
+| [UC-01](./uc-01-endpoint-auto-repair.md) | Endpoint activation — independent auto repair | Model 1 | Spec |
+| [UC-02](./uc-02-intermediate-tourism-board.md) | Intermediate activation — destination tourism board | Model 2 | Spec |
+
+## How to write more of these
+
+Use the same template as UC-01/UC-02:
+
+- Problem and context  
+- Primary actor and stakeholders  
+- Preconditions  
+- Main success scenario (numbered)  
+- Alternate and exception paths  
+- Success metrics  
+- Explicit out of scope  
+- Open questions  
+
+If a use case only restates strategy prose, it is not ready. If it cannot drive a sprint ticket, it is not ready.