refactor(topology): make the 12-kinds-to-5-patterns collapse explicit

TopologyKind describes twelve distinct intents, but the orchestrator
implements five planners and mapped the kinds onto them inside plan_steps.
So Market never auctions, StarMoe never routes to experts, Ring never cycles
and Holacratic never self-organizes -- each silently runs as whichever pattern
it collapses to, while kind::description() and the UI catalog kept promising
the distinct behaviour.

Rather than delete variants that appear in persisted rows, the collapse is now
named: ExecutionPattern + TopologyKind::execution_pattern() in cm-topology,
with plan_steps dispatching on the pattern instead of re-listing the mapping.
One source of truth, and the two cannot drift.

GET /api/topologies now reports `executes_as` and `distinct_at_execution` so a
UI can stop offering aliases as if they behaved differently.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

crates/cm-api/src/routes/topology.rs

@@ -33,6 +33,13 @@ pub struct CatalogEntry {
     pub name: String,
     pub description: String,
     pub role_distribution: Vec<RoleWeight>,
+    /// The execution pattern this kind actually runs as. Twelve kinds map onto
+    /// five patterns, so this differs from `name` for the aliased ones.
+    pub executes_as: String,
+    /// False when the kind is an alias — its description promises semantics the
+    /// engine does not implement (Market never auctions, Ring never cycles).
+    /// A UI should not offer these as if they behaved differently.
+    pub distinct_at_execution: bool,
 }
 
 /// `GET /api/topologies` — the catalog of supported topology kinds.
@@ -53,6 +60,8 @@ pub async fn catalog(_auth: Authed) -> Json<Vec<CatalogEntry>> {
                         weight: *weight,
                     })
                     .collect(),
+                executes_as: kind.execution_pattern().as_str().to_string(),
+                distinct_at_execution: kind.is_distinct_at_execution(),
             }
         })
         .collect();