Read a descriptor's variants without taking them

Two agents worked in parallel and neither could see this. The frame-budget
instrument matches `ParamKind::Enum { variants }` by value, which was free when
a descriptor was `&'static` and everything in it was borrowed for the life of
the program. Descriptors are owned now — a declaration parsed at run time
cannot hand out a `&'static` — so `variants` is a `Vec` and the arm was moving
out of a shared reference.

Bound by reference instead. The arm only ever reads the length.

The kind of conflict that survives a clean textual merge: git had nothing to
report, and the two changes are only incompatible once they are in the same
tree.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

core/dr-gpu/examples/frame_budget.rs

@@ -634,7 +634,10 @@ fn activate_everything(graph: &mut EditGraph, neighbourhood: bool) {
                     ParamKind::Bool => 1.0,
                     // The second variant when there is one. The first is the
                     // default by construction — see `ParamDescriptor::choice`.
-                    ParamKind::Enum { variants } => {
+                    // Bound by reference: a descriptor's variants became an
+                    // owned `Vec` when descriptors stopped being `&'static`,
+                    // and this arm only ever reads the length.
+                    ParamKind::Enum { ref variants } => {
                         if variants.len() > 1 {
                             1.0
                         } else {

core/dr-gpu/tests/frame_budget.rs

@@ -282,7 +282,10 @@ fn full_point_chain() -> EditGraph {
                         p.default + (far - p.default) * 0.25
                     }
                     ParamKind::Bool => 1.0,
-                    ParamKind::Enum { variants } => {
+                    // Bound by reference: a descriptor's variants became an
+                    // owned `Vec` when descriptors stopped being `&'static`,
+                    // and this arm only ever reads the length.
+                    ParamKind::Enum { ref variants } => {
                         if variants.len() > 1 {
                             1.0
                         } else {