Prune commentary and stale Rust port notes

docs/IRIS_TODO.md

@@ -1,14 +1,6 @@
 # iris: known problems and things still to build
 
-Iris's own list for the library, recorded 2026-09-04 in her words where it
-matters, so the work in RUST.md picks these up in a sensible order rather
-than rediscovering them. Each item says where it sits in the order and
-what "done" looks like.
-
-**Only open items live here.** An item is deleted when it lands, not
-ticked: a list of finished work is context every future session pays for,
-and what a change did belongs at the code it changed. Fifty closed items
-and six phone-report sections went on 2026-09-08 for that reason.
+Only open Iris framework work lives here. Delete an item when it lands.
 
 ## Fix
 
@@ -20,12 +12,8 @@ and six phone-report sections went on 2026-09-08 for that reason.
   (17,17,27) became (73,73,91) in a desktop screenshot measured on
   2026-09-06.
 
-  The earlier entry called this desktop-only because the Android picture
-  looked right. That was not a measurement: neither the startup line nor
-  the diagnostics report records the selected surface format, and the
-  Android backend contains the identical preference and shader path. A
-  device exposing only a non-sRGB surface can happen to hide the bug; it
-  does not make the pipeline correct.
+  Neither diagnostics nor startup logging records Android's selected surface
+  format. A device exposing only a non-sRGB surface can hide the shared bug.
 
   Done means defining one convention for palette bytes, decoded images,
   colour emoji and the clear colour, then converting exactly once for the
@@ -33,12 +21,10 @@ and six phone-report sections went on 2026-09-08 for that reason.
   test that draws known non-black, non-white pixels into an sRGB target and
   reads the stored bytes back; screenshots from desktop and Android then
   confirm the same Catppuccin values rather than serving as the definition.
+
 ## Build (for the port)
 
-Widgets `RUST.md`'s "The port, in order (decided 2026-09-05)" needs and
-iris does not have yet, one entry per gap, named against the P-step that
-first needs it. Move an entry up to "Fix" if it becomes a current defect;
-delete it once built rather than duplicating it there.
+Framework capabilities needed by `RUST.md`'s port plan:
 
 - [ ] **Selectable, read-only text.** P0's report and P1's transcript rows
   use `TextEdit` because `Selectable` is implemented only for it. That
@@ -88,18 +74,14 @@ delete it once built rather than duplicating it there.
   `Widget::tick` and `UiData::animate`. A widget that does not opt in must
   pay nothing and import nothing for them.
 
-- [ ] **Remove `WidgetView` unless a real composite adopts it first.** The
-  layout change this decision was waiting for has landed. Every composite
-  in `app-rust/src/ui` now uses ordinary child handles plus a returned root;
+- [ ] **Remove `WidgetView` unless a real composite adopts it.** Every
+  composite in `app-rust/src/ui` uses ordinary child handles plus a root;
   `WidgetView` and its derive are used only by `iris/examples/view.rs`.
-  Today it demonstrates itself rather than shortening production code, so
-  deletion is the concrete default—not another parallel composition style.
+  It currently demonstrates itself rather than shortening production code.
 
 - [ ] **A `Stack` that chooses its mask the way it chooses its size
-  (Iris, 2026-09-08).** She asked whether `masked_by` deserves to exist:
-  "a method that just does 2 separate things you can already easily do
-  does not deserve to exist." For a square-cornered surface it is indeed
-  redundant -- `.background(rect(BAR_FILL)).masked()` was measured
+  should replace `masked_by`.** For a square-cornered surface,
+  `.background(rect(BAR_FILL)).masked()` was measured
   against `.masked_by(rect(BAR_FILL))` on the composer at the phone's own
   size and density and the two are identical to the pixel. What the pair
   cannot express is a clip that is not a box: `Painter::set_mask` writes