Put the coordinate-domain lens corrections into the graph

`lens.rs` has held a `Warp` trait, a composer and two implementations —
distortion and lateral chromatic aberration — since they were written, and
`compose_warps` was called by nothing outside its own tests. The corrections
existed, were correct, and never touched a photograph.

`EditGraph` now holds them, and `compose_full` emits them between the framing
prologue and the fetch. Distortion first, then CA: each warp receives the
position the previous one produced, and lateral CA is a magnification about
the optical axis of the *undistorted* frame, so measured on a barrel-distorted
one it would be fitted to a radius no profile describes.

They reach the panel the way framing already does — through `capabilities`.
That was the one open question and existing practice answered it: framing is
also not an `Operation`, also has parameters a photographer sets, and also
arrives through that list. Because `Preset::capture` walks the same list, the
sidecar, the clipboard and the undo stack carry a warp's parameters with
nothing registered anywhere, and no file under `ui/` names one (FR-DEV-3a).

`state()` destructures `EditGraph` field by field precisely so that a new
field cannot be forgotten, and it was not.

Chromatic aberration is the only thing that samples per channel, and
`splits_channels` is what keeps everything else from paying for it. Red and
blue are fetched from positions green is not — green is the reference and
never moves, so a wrong correction still leaves one channel sharp rather than
softening all three. With no CA in the chain the single-fetch path is emitted
instead.

The interpolating sampler is now chosen by framing *or* an active warp. Asking
framing alone would have nearest-neighboured a distortion correction on an
unstraightened frame, and that aliasing reads as a bad profile rather than as
a missing filter.

The warps go in the geometry invalidation key rather than the colour one: they
decide which source pixel a colour is read from, so a tile cached across a
distortion change would keep drawing the previous correction. The pipeline
cache needs nothing new — `hash_source` already covers the generated body, and
uniform values never enter it, so arming a warp recompiles and dragging it
does not. Both are asserted.

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

core/dr-gpu/examples/local.rs

@@ -335,6 +335,7 @@ fn render_stack(
         ColourSpace::Srgb,
         stack,
         &SpotSet::new(),
+        &[],
     );
     adjust
         .render_masked(source, &shader, ow, oh, Some(array))