Hand out descriptors a declaration could produce

`Operation::descriptor()` returned `&'static OpDescriptor`, and that lifetime
is the whole reason a build-time node is free and a run-time node is
impossible: only a compile-time literal can satisfy it, so no amount of
reading `ops/*.yaml` at startup could ever produce a descriptor the rest of
the application would accept. FR-PLG-2 says a bundled operation and a
third-party plugin are the same kind of thing, differing only in where the
file was found — and a lifetime outsiders cannot meet is exactly the second,
weaker format that requirement forbids.

So a descriptor is now owned and handed out as `Arc<OpDescriptor>`, with `Vec`
where it held `&'static` slices. `Arc` rather than a `&self`-borrowed
reference because the callers want to *keep* it: the develop panel collects
descriptors and then mutates the graph, and a borrow would tie the
descriptor's lifetime to a borrow of the operation it came from, which is the
one thing `&'static` was doing right.

The identifier newtypes deliberately did not follow. `ParamId` is `Copy`, is
compared in `match` arms against generated constants, is a map key in the
sidecar and history, and reaches Slint model rows; an `Arc<str>` there would
cost a refcount on every one of those and would take `match id { EXPOSURE =>
.. }` away from the generated code. They gain an interner instead, which is
honest about its lifetime rather than pretending to one — the set of ids is
bounded by deduplication and is process-lifetime by construction, because the
sidecar on disk names its parameters and an id has to stay resolvable for as
long as any edit naming it can be opened.

No behaviour changes. Every descriptor that was a `static` is a `LazyLock`
initialiser now, `Operation::helpers` borrows from `self` instead of being
`'static` so a future run-time node can own its list, and `Warp` and `Framing`
follow `Operation` so there is one shape rather than two.

The one place a descriptor is read per frame is `compose_full`, which takes
`descriptor().id` to prefix each active operation's uniforms, and `dr-ui`
composes on every frame it draws. That is a dozen atomic increments beside a
composition that is already building several kilobytes of WGSL on the same
call; it is noted at the trait method rather than left for a profiler to find.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

core/dr-pipeline/src/ops/vignetting.rs

@@ -32,6 +32,7 @@
 //! division is the whole reason this operation must run before the tonal
 //! stages: a corner recovered by two stops has to be recovered while the
 //! highlight headroom to hold it still exists (ARCH §5.2).
+use std::sync::{Arc, LazyLock};
 
 use crate::descriptor::{Attribute, LocalizedKey, OpDescriptor, OpId, ParamDescriptor, ParamId};
 use crate::operation::{Helper, Operation, Uniform};
@@ -45,19 +46,21 @@ pub const AMOUNT: ParamId = ParamId("amount");
 /// fast prime wide open — the case that actually needs correcting.
 const MAX_K1: f32 = -0.5;
 
-static DESCRIPTOR: OpDescriptor = OpDescriptor {
-    // Optics rather than effect: this carries lens-profile coefficients
-    // and corrects what the lens did. A *creative* vignette is a different
-    // operation that does not exist yet, and would be `Effect`.
-    attributes: &[Attribute::Optics],
-    id: ID,
-    label: LocalizedKey("op.vignetting"),
-    // Bidirectional deliberately. Negative values *add* falloff, which is a
-    // legitimate creative choice as well as a correction, and a control that
-    // only removed vignetting would need a second one beside it to put any
-    // back.
-    params: &[ParamDescriptor::amount("amount", "param.vignetting.amount")],
-};
+static DESCRIPTOR: LazyLock<Arc<OpDescriptor>> = LazyLock::new(|| {
+    Arc::new(OpDescriptor {
+        // Optics rather than effect: this carries lens-profile coefficients
+        // and corrects what the lens did. A *creative* vignette is a different
+        // operation that does not exist yet, and would be `Effect`.
+        attributes: vec![Attribute::Optics],
+        id: ID,
+        label: LocalizedKey("op.vignetting"),
+        // Bidirectional deliberately. Negative values *add* falloff, which is a
+        // legitimate creative choice as well as a correction, and a control that
+        // only removed vignetting would need a second one beside it to put any
+        // back.
+        params: vec![ParamDescriptor::amount("amount", "param.vignetting.amount")],
+    })
+});
 
 /// The `pa` polynomial coefficients, as Lensfun stores them.
 #[derive(Debug, Clone, Copy, PartialEq)]
@@ -107,8 +110,8 @@ impl Vignetting {
 }
 
 impl Operation for Vignetting {
-    fn descriptor(&self) -> &'static OpDescriptor {
-        &DESCRIPTOR
+    fn descriptor(&self) -> Arc<OpDescriptor> {
+        DESCRIPTOR.clone()
     }
 
     fn set_param(&mut self, id: ParamId, value: f32) {
@@ -371,7 +374,7 @@ mod tests {
     #[test]
     fn every_default_is_neutral() {
         let mut v = Vignetting::new();
-        for p in DESCRIPTOR.params {
+        for p in &DESCRIPTOR.params {
             v.set_param(p.id, p.default);
         }
         assert!(!v.is_active());