Prune commentary and stale Rust port notes

scripts/rigs/ui-profile/Cargo.toml

@@ -1,22 +1,10 @@
-# The UI profiling rigs: what a frame costs on the CPU, and what each GPU
-# arena costs to upload. Layer 1 of docs/RUST.md's "Three test layers" --
-# the real transcript screen over the real bench fixture, with no window,
-# no compositor and no GPU.
-#
-# **Its own crate so a rig's dependencies stay out of the app's** (Iris,
-# 2026-09-09). `bytemuck` is here because `arena_churn` reads the arenas
-# as bytes; nothing in `ai-app` needs it, and a dev-dependency there would
-# put it in the graph of every `cargo test` the app runs.
-#
-# Deliberately not a member of any workspace, for the same reason
-# `gpu-probe` is not: `iris/` is meant to stay reconcilable with the
-# upstream iris tree, and these belong to ai-app.
+# Standalone so profiling dependencies stay out of the app and iris workspaces.
 [package]
 name = "ui-profile"
 version = "0.1.0"
 edition = "2024"
 
-[dependencies]
+[dev-dependencies]
 ai-app = { path = "../../../app-rust" }
 iris = { path = "../../../iris" }
 bytemuck = "1"