Stop describing a base curve the pipeline no longer has

D19 retired the per-body base curve, moved the matrix ahead of the
edits and the film into the view transform's place, but a dozen doc
comments still listed the curve among what a pixel passes through, or
said the film skipped it. The detail stage's module doc still drew the
matrix after the edits and the last detail pass encoding, which the
view pass took over. The film crate's README gave the base curves as
its reason for being data, and the ops README's list of hand-written
nodes had neither the view transform nor three of the five kernels.

FR-MRG-2 gave the base curve as why the merge cuts below the profile;
the view transform is why now. The decision table still said colour
defaults were a per-body curve, and FR-DEV-3j said only the default
view transform skips a JPEG, where the node skips one whatever its
sliders say. frame-budget.md records the view pass as unmeasured.

core/dr-pipeline/src/descriptor.rs

@@ -659,10 +659,10 @@ impl Attribute {
     ///
     /// `Effect` after `Colour` is a look laid over a settled picture — and is
     /// the one arguable slot. A spectral film simulation declares
-    /// [`crate::Operation::renders`] and replaces the base curve, which is an
-    /// argument for treating it as foundational rather than final; an array of
-    /// six cannot say "last, except when it is first". The tension is recorded
-    /// here rather than settled.
+    /// [`crate::Operation::renders`] and takes the view transform's place at
+    /// the very end of the chain (D19), which is an argument for treating it as
+    /// the rendering rather than one effect among others; an array of six
+    /// cannot say that. The tension is recorded here rather than settled.
     ///
     /// Both ends were wrong for as long as this list only fed a row of chips
     /// nobody reads in order. It stopped being harmless when the same list