Add post-processing audio effects system

Adds a full effects pipeline powered by Spotify's pedalboard library,
enabling users to apply professional DSP effects (flanger, reverb, delay,
compressor, pitch shift, filters, gain) to generated audio.

Key features:
- Effects chain editor with drag-and-drop reordering (dnd-kit)
- Generation versions: clean copy always saved, processed versions created on top
- Built-in presets (Robotic, Radio, Echo Chamber, Deep Voice) + custom user presets
- Per-profile default effects chain (auto-applied to new generations)
- Per-generation effects override from the generation form
- Apply effects to existing generations from history (creates new version)
- Ephemeral preview endpoint for auditioning effects without persisting
- Dedicated Effects sidebar tab with preset management and live preview
- Version switcher in history cards with expandable panel
- Backward-compatible: existing generations backfilled as clean versions

app/src/router.tsx

@@ -1,6 +1,7 @@
 import { createRootRoute, createRoute, createRouter, Outlet } from '@tanstack/react-router';
 import { AppFrame } from '@/components/AppFrame/AppFrame';
 import { AudioTab } from '@/components/AudioTab/AudioTab';
+import { EffectsTab } from '@/components/EffectsTab/EffectsTab';
 import { MainEditor } from '@/components/MainEditor/MainEditor';
 import { ModelsTab } from '@/components/ModelsTab/ModelsTab';
 import { ServerTab } from '@/components/ServerTab/ServerTab';
@@ -105,6 +106,13 @@ const audioRoute = createRoute({
   component: AudioTab,
 });
 
+// Effects route
+const effectsRoute = createRoute({
+  getParentRoute: () => rootRoute,
+  path: '/effects',
+  component: EffectsTab,
+});
+
 // Models route
 const modelsRoute = createRoute({
   getParentRoute: () => rootRoute,
@@ -125,6 +133,7 @@ const routeTree = rootRoute.addChildren([
   storiesRoute,
   voicesRoute,
   audioRoute,
+  effectsRoute,
   modelsRoute,
   serverRoute,
 ]);