feat(denoise): add self-hosted DeepFilterNet 3 ML noise-suppression model

Integrate DeepFilterNet 3 (deepfilternet3-noise-filter@1.2.1) as a new
client-side denoise model id 'deepfilternet', mirroring the DTLN pattern.

The npm package ships only an ESM whose AudioWorklet processor + wasm-bindgen
glue are inlined as a string (loaded via a Blob URL — no CDN for the worklet).
Its only runtime fetches are a single-threaded df_bg.wasm and an ONNX model
tarball, which previously loaded from an external CDN. We now VENDOR both
(build/denoise-vendor/deepfilternet/v2/...) and self-host them under
denoise/deepfilternet/, overriding the package's cdnUrl so nothing hits the
upstream CDN — keeping it self-hosted / Tauri-CSP safe.

The wasm is single-threaded (no SharedArrayBuffer / atomics / imported shared
memory), so it needs no COOP/COEP cross-origin isolation and runs fine in EC's
non-isolated iframe. Runs at 48 kHz fullband. Any init/runtime failure falls
back to the raw mic, like the other models.

- vite.config.js: copy ESM + vendored wasm/model into the EC denoise dir with a
  required-asset guard that aborts the build if any entry is missing.
- build/lotus-denoise.js: 'deepfilternet' branch — dynamic-import the ESM, build
  a DeepFilterNet3Core pointed at the self-hosted base, await init, return the
  worklet node; 48 kHz; raw-mic fail-safe preserved.
- denoisePipeline.ts: 'deepfilternet' branch for the in-app tester + sampleRate.
- settings.ts: add 'deepfilternet' to DenoiseModelId + getSettings whitelist.
- lotusDenoiseUtils.ts: add the comparison-chart row.
- General.tsx: add the "DeepFilterNet 3 (beta)" dropdown option.

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

package-lock.json

@@ -35,6 +35,7 @@
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         "dateformat": "5.0.3",
         "dayjs": "1.11.20",
+        "deepfilternet3-noise-filter": "1.2.1",
         "domhandler": "6.0.1",
         "dompurify": "3.4.5",
         "emojibase": "17.0.0",
@@ -6399,6 +6400,18 @@
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       "dev": true
     },
+    "node_modules/deepfilternet3-noise-filter": {
+      "version": "1.2.1",
+      "resolved": "https://registry.npmjs.org/deepfilternet3-noise-filter/-/deepfilternet3-noise-filter-1.2.1.tgz",
+      "integrity": "sha512-OAyrHTDlUHH+AhfpVNKYEOhVqb9cZpu0fdNThplA/tB/Ts4PF/UsI+abl2n1IbSxUkhiF0OqDejEhk1n42Oqpw==",
+      "license": "(Apache-2.0 OR MIT)",
+      "engines": {
+        "node": ">=18.0.0"
+      },
+      "peerDependencies": {
+        "livekit-client": "^2.0.0"
+      }
+    },
     "node_modules/deepmerge": {
       "version": "4.3.1",
       "resolved": "https://registry.npmjs.org/deepmerge/-/deepmerge-4.3.1.tgz",