chore: drop a dead audio-FX ignoreExports entry

Both symbols the entry named are gone: `AUDIO_FX_WORKLET_SOURCE` is a
module-private const rather than an export, and `__resetAudioFxWorkletsForTests`
does not exist at all. The entry has been inert since c3291f2 added it, and an
ignore that names nothing only makes the next reader look for something that
is not there.

Left alone deliberately: the file-scoped `health.ignore` on
`packages/core/src/runtime/media.ts`. It is over-broad — its comment says it is
for `refreshRuntimeMediaCache`, but it also exempts `syncRuntimeMedia`, which
IS what this stack changed. `health.ignore` takes file paths only, so there is
no way to narrow it in config; removing it wants a fallow run to confirm what
it then reports, and fallow already fails on this stack.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: vanceingalls

.fallowrc.jsonc

@@ -149,13 +149,6 @@
       "file": "packages/studio/src/utils/studioHelpers.ts",
       "exports": ["resolveDroppedAssetDimensions"],
     },
-    // Audio FX worklets sit near the bottom of the audio stack: the worklet
-    // source and its test reset are consumed by the runtime and engine PRs
-    // upstack, so a per-PR audit against the merge base sees them as unused.
-    {
-      "file": "packages/core/src/audio/audioFxWorklets.ts",
-      "exports": ["AUDIO_FX_WORKLET_SOURCE", "__resetAudioFxWorkletsForTests"],
-    },
     {
       "file": "packages/core/src/audio/audioFxGraph.ts",
       "exports": ["ensureAudioFxWorklets"],