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/features/settings/general/DenoiseTester.tsx

@@ -1,6 +1,7 @@
 import React, { useCallback, useEffect, useRef, useState } from 'react';
 import { Box, Button, Text } from 'folds';
 import { DenoiseModelId } from '../../../state/settings';
+import { DENOISE_MODELS } from '../../../utils/lotusDenoiseUtils';
 import {
   DenoiseNode,
   buildGateNode,
@@ -307,7 +308,7 @@ export function DenoiseTester({ model, useGate, gateThreshold, nativeNS }: Denoi
     [stopLive, stopPlayback],
   );
 
-  const modelLabel = model === 'rnnoise' ? 'RNNoise' : model === 'speex' ? 'Speex' : 'DTLN';
+  const modelLabel = DENOISE_MODELS.find((m) => m.id === model)?.name ?? model;
 
   return (
     <Box direction="Column" gap="400">
@@ -367,6 +368,7 @@ export function DenoiseTester({ model, useGate, gateThreshold, nativeNS }: Denoi
                 { label: 'RNNoise', model: 'rnnoise' },
                 { label: 'Speex', model: 'speex' },
                 { label: 'DTLN', model: 'dtln' },
+                { label: 'DeepFilterNet', model: 'deepfilternet' },
               ] as const
             ).map((b) => (
               <Button