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-topology/src/lib.rs

@@ -26,7 +26,7 @@ pub use builders::build;
 pub use classifier::{classify, Classification, GraphMetrics};
 pub use graph::{Edge, EdgeKind, Node, TopologyGraph};
 pub use heuristics::{heuristics, Heuristics};
-pub use kind::TopologyKind;
+pub use kind::{ExecutionPattern, TopologyKind};
 
 /// Errors produced while building or validating a topology.
 #[derive(Debug, thiserror::Error, PartialEq, Eq)]