Reorganize ML noise suppression settings UI

Move the model comparison out of the always-visible Noise Suppression
description and into the ML-only sub-settings. Add a compact info card
for the selected model (CPU / voice quality / transients / download) plus
a collapsible 4-model comparison. Group ML sub-settings into Model,
Enhancements, and Test & calibrate sections with clear labels and
separators. Fix invented --lt-border-color token and hardcoded
rgba background to real TDS tokens. Build the model dropdown and
DenoiseTester labels/compare buttons from DENOISE_MODELS so
DeepFilterNet 3 is handled correctly.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/utils/lotusDenoiseUtils.ts

@@ -2,8 +2,10 @@
  * Detection utilities for Lotus ML noise suppression (RNNoise).
  */
 
+import { DenoiseModelId } from '../state/settings';
+
 export type DenoiseModel = {
-  id: string;
+  id: DenoiseModelId;
   name: string;
   description: string;
   cpuUsage: string;