feat: model management improvements and folder migration

- Add model folder migration with byte-level progress tracking (backend + UI)
- Custom models directory support via VOICEBOX_MODELS_DIR env var passed to sidecar
- Hardcoded model descriptions displayed in model detail cards
- Open model folder button in storage location row
- Remove 'not downloaded' badge from model cards
- Fix server settings scroll offset for audio player
- Fix shell open permission to allow file paths
- Add normalize toggle to generation settings

app/src/lib/api/client.ts

@@ -316,6 +316,21 @@ class ApiClient {
     return this.request<ModelStatusListResponse>('/models/status');
   }
 
+  async getModelsCacheDir(): Promise<{ path: string }> {
+    return this.request<{ path: string }>('/models/cache-dir');
+  }
+
+  async migrateModels(destination: string): Promise<{ source: string; destination: string }> {
+    return this.request('/models/migrate', {
+      method: 'POST',
+      body: JSON.stringify({ destination }),
+    });
+  }
+
+  getMigrationProgressUrl(): string {
+    return `${this.getBaseUrl()}/models/migrate/progress`;
+  }
+
   async triggerModelDownload(modelName: string): Promise<{ message: string }> {
     console.log(
       '[API] triggerModelDownload called for:',

app/src/lib/api/types.ts

@@ -38,6 +38,7 @@ export interface GenerationRequest {
   instruct?: string;
   max_chunk_chars?: number;
   crossfade_ms?: number;
+  normalize?: boolean;
 }
 
 export interface GenerationResponse {

app/src/lib/hooks/useGenerationForm.ts

@@ -34,6 +34,7 @@ export function useGenerationForm(options: UseGenerationFormOptions = {}) {
   const setIsGenerating = useGenerationStore((state) => state.setIsGenerating);
   const maxChunkChars = useServerStore((state) => state.maxChunkChars);
   const crossfadeMs = useServerStore((state) => state.crossfadeMs);
+  const normalizeAudio = useServerStore((state) => state.normalizeAudio);
   const [downloadingModelName, setDownloadingModelName] = useState<string | null>(null);
   const [downloadingDisplayName, setDownloadingDisplayName] = useState<string | null>(null);
 
@@ -115,6 +116,7 @@ export function useGenerationForm(options: UseGenerationFormOptions = {}) {
         instruct: isQwen ? data.instruct || undefined : undefined,
         max_chunk_chars: maxChunkChars,
         crossfade_ms: crossfadeMs,
+        normalize: normalizeAudio,
       });
 
       toast({

app/src/lib/hooks/useRestoreActiveTasks.tsx

@@ -1,23 +1,23 @@
 import { useCallback, useEffect, useRef, useState } from 'react';
 import { apiClient } from '@/lib/api/client';
-import { useGenerationStore } from '@/stores/generationStore';
 import type { ActiveDownloadTask } from '@/lib/api/types';
+import { useGenerationStore } from '@/stores/generationStore';
 
 // Polling interval in milliseconds
-const POLL_INTERVAL = 2000;
+const POLL_INTERVAL = 30000;
 
 /**
  * Hook to monitor active tasks (downloads and generations).
  * Polls the server periodically to catch downloads triggered from anywhere
  * (transcription, generation, explicit download, etc.).
- * 
+ *
  * Returns the active downloads so components can render download toasts.
  */
 export function useRestoreActiveTasks() {
   const [activeDownloads, setActiveDownloads] = useState<ActiveDownloadTask[]>([]);
   const setIsGenerating = useGenerationStore((state) => state.setIsGenerating);
   const setActiveGenerationId = useGenerationStore((state) => state.setActiveGenerationId);
-  
+
   // Track which downloads we've seen to detect new ones
   const seenDownloadsRef = useRef<Set<string>>(new Set());
 
@@ -41,14 +41,14 @@ export function useRestoreActiveTasks() {
       // Update active downloads
       // Keep track of all active downloads (including new ones)
       const currentDownloadNames = new Set(tasks.downloads.map((d) => d.model_name));
-      
+
       // Remove completed downloads from our seen set
       for (const name of seenDownloadsRef.current) {
         if (!currentDownloadNames.has(name)) {
           seenDownloadsRef.current.delete(name);
         }
       }
-      
+
       // Add new downloads to seen set
       for (const download of tasks.downloads) {
         seenDownloadsRef.current.add(download.model_name);