Add request approval system and audiobook path template

Implements admin approval workflow for user requests with global and per-user auto-approve controls. Adds new request statuses ('awaiting_approval', 'denied'), related API endpoints, and UI for pending approvals. Introduces configurable audiobook organization path template with validation and preview in settings, updates database schema and migrations for new fields.

src/app/admin/settings/tabs/PathsTab/PathsTab.tsx

@@ -5,11 +5,12 @@
 
 'use client';
 
-import React from 'react';
+import React, { useState, useEffect } from 'react';
 import { Button } from '@/components/ui/Button';
 import { Input } from '@/components/ui/Input';
 import { usePathsSettings } from './usePathsSettings';
 import type { PathsSettings } from '../../lib/types';
+import { validateTemplate, generateMockPreviews } from '@/lib/utils/path-template.util';
 
 interface PathsTabProps {
   paths: PathsSettings;
@@ -24,6 +25,31 @@ export function PathsTab({ paths, onChange, onValidationChange }: PathsTabProps)
     onValidationChange,
   });
 
+  // Live preview state (client-side validation)
+  const [livePreview, setLivePreview] = useState<{
+    isValid: boolean;
+    error?: string;
+    previewPaths?: string[];
+  } | null>(null);
+
+  // Update live preview whenever template changes
+  useEffect(() => {
+    const template = paths.audiobookPathTemplate || '{author}/{title} {asin}';
+    const validation = validateTemplate(template);
+
+    if (validation.valid) {
+      setLivePreview({
+        isValid: true,
+        previewPaths: generateMockPreviews(template),
+      });
+    } else {
+      setLivePreview({
+        isValid: false,
+        error: validation.error,
+      });
+    }
+  }, [paths.audiobookPathTemplate]);
+
   return (
     <div className="space-y-6 max-w-2xl">
       <div>
@@ -69,6 +95,78 @@ export function PathsTab({ paths, onChange, onValidationChange }: PathsTabProps)
         </p>
       </div>
 
+      {/* Audiobook Organization Template */}
+      <div>
+        <label className="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-2">
+          Audiobook Organization Template
+        </label>
+        <Input
+          type="text"
+          value={paths.audiobookPathTemplate || '{author}/{title} {asin}'}
+          onChange={(e) => updatePath('audiobookPathTemplate', e.target.value)}
+          placeholder="{author}/{title} {asin}"
+          className="font-mono"
+        />
+        <p className="text-sm text-gray-500 dark:text-gray-400 mt-1">
+          Customize how audiobooks are organized within the media directory
+        </p>
+
+        {/* Variable Reference Panel */}
+        <div className="mt-4 bg-blue-50 dark:bg-blue-900/20 border border-blue-200 dark:border-blue-800 rounded-lg p-4">
+          <h3 className="text-sm font-semibold text-blue-900 dark:text-blue-100 mb-3">
+            Available Variables
+          </h3>
+          <div className="grid grid-cols-1 sm:grid-cols-2 gap-2 text-sm">
+            <div>
+              <code className="text-blue-700 dark:text-blue-300 font-mono">{'{author}'}</code>
+              <span className="text-gray-600 dark:text-gray-400 ml-2">- Book author</span>
+            </div>
+            <div>
+              <code className="text-blue-700 dark:text-blue-300 font-mono">{'{title}'}</code>
+              <span className="text-gray-600 dark:text-gray-400 ml-2">- Book title</span>
+            </div>
+            <div>
+              <code className="text-blue-700 dark:text-blue-300 font-mono">{'{narrator}'}</code>
+              <span className="text-gray-600 dark:text-gray-400 ml-2">- Narrator name</span>
+            </div>
+            <div>
+              <code className="text-blue-700 dark:text-blue-300 font-mono">{'{year}'}</code>
+              <span className="text-gray-600 dark:text-gray-400 ml-2">- Release year</span>
+            </div>
+            <div>
+              <code className="text-blue-700 dark:text-blue-300 font-mono">{'{asin}'}</code>
+              <span className="text-gray-600 dark:text-gray-400 ml-2">- Audible ASIN</span>
+            </div>
+          </div>
+        </div>
+
+        {/* Live Preview - Client-side validation */}
+        {livePreview && !livePreview.isValid && (
+          <div className="mt-3 p-3 rounded-lg text-sm flex items-start gap-2 bg-red-50 dark:bg-red-900/20 border border-red-200 dark:border-red-800 text-red-800 dark:text-red-200">
+            <span className="flex-shrink-0 mt-0.5">✗</span>
+            <div className="flex-1">
+              <span>{livePreview.error || 'Invalid template format'}</span>
+            </div>
+          </div>
+        )}
+
+        {/* Live Preview Examples - Show while editing */}
+        {livePreview && livePreview.isValid && livePreview.previewPaths && (
+          <div className="mt-3 bg-gray-50 dark:bg-gray-800 border border-gray-200 dark:border-gray-700 rounded-lg p-4">
+            <h4 className="text-sm font-semibold text-gray-900 dark:text-gray-100 mb-2">
+              Preview Examples
+            </h4>
+            <div className="space-y-1.5 text-sm font-mono text-gray-700 dark:text-gray-300">
+              {livePreview.previewPaths.map((preview, index) => (
+                <div key={index} className="text-xs">
+                  {paths.mediaDir || '/media/audiobooks'}/{preview}
+                </div>
+              ))}
+            </div>
+          </div>
+        )}
+      </div>
+
       {/* Metadata Tagging Toggle */}
       <div className="bg-gray-50 dark:bg-gray-800 rounded-lg p-4 border border-gray-200 dark:border-gray-700">
         <div className="flex items-start gap-4">

src/app/admin/settings/tabs/PathsTab/usePathsSettings.ts

@@ -27,7 +27,7 @@ export function usePathsSettings({ paths, onChange, onValidationChange }: UsePat
   };
 
   /**
-   * Test if paths are valid and writable
+   * Test if paths are valid and writable, including template validation
    */
   const testPaths = async () => {
     setTesting(true);
@@ -40,6 +40,7 @@ export function usePathsSettings({ paths, onChange, onValidationChange }: UsePat
         body: JSON.stringify({
           downloadDir: paths.downloadDir,
           mediaDir: paths.mediaDir,
+          audiobookPathTemplate: paths.audiobookPathTemplate,
         }),
       });
 
@@ -48,7 +49,8 @@ export function usePathsSettings({ paths, onChange, onValidationChange }: UsePat
       if (data.success) {
         const result: TestResult = {
           success: true,
-          message: 'All paths are valid and writable'
+          message: 'All paths are valid and writable',
+          templateValidation: data.template
         };
         setTestResult(result);
         onValidationChange(true);
@@ -56,10 +58,13 @@ export function usePathsSettings({ paths, onChange, onValidationChange }: UsePat
       } else {
         const result: TestResult = {
           success: false,
-          message: data.error || 'Path validation failed'
+          message: data.error || 'Path validation failed',
+          templateValidation: data.template
         };
         setTestResult(result);
-        onValidationChange(false);
+        // Only mark as valid if paths are valid AND template is valid (if provided)
+        const isValid = false;
+        onValidationChange(isValid);
         return result;
       }
     } catch (error) {