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/genre-packs.md

@@ -4,15 +4,19 @@ Generic business fields are scaffolding. Durable differentiation is **genre-spec
 
 ## Planned early packs
 
-- Auto repair  
+- Auto repair (see [UC-01](./use-cases/uc-01-endpoint-auto-repair.md))  
 - Beauty  
 - Home services  
-- Tourism activity (especially with destination pilots)
+- Tourism activity (especially with destination pilots / [UC-02](./use-cases/uc-02-intermediate-tourism-board.md))
 
-## Detail source
+## Why this matters
 
-[Canonical Strategy](../strategy/CANONICAL_STRATEGY.md) (§5.3).
+Assistants evaluate helpfulness partly by whether the business answers the *right* questions for its category. “Do you work on Korean transmissions?” is not the same shape as “Do you have a sunset charter tomorrow for six?”
 
 ## Repo note (future)
 
-Genre packs will live under top-level `genres/` in a later monorepo phase. Product intent is documented here first.
+Genre packs will live under top-level `genres/` in a later monorepo phase. Product intent and use-case contracts stay here first.
+
+## Detail source
+
+[Canonical Strategy](../strategy/CANONICAL_STRATEGY.md) (genre-specific primitives).