feat: standardize download path configuration and auto-migrate .env

- Change DOWNLOAD_PATH to Library__DownloadPath (ASP.NET Core standard)
- Add EnvMigrationService to automatically update old .env files on startup
- Update .env.example with new variable name
- Ensures cache cleanup and downloads use consistent path configuration
- No manual intervention needed - migration happens automatically

.env.example

@@ -40,7 +40,7 @@ MUSIC_SERVICE=SquidWTF
 # - downloads/permanent/ - Permanently downloaded tracks (STORAGE_MODE=Permanent)
 # - downloads/cache/ - Temporarily cached tracks (STORAGE_MODE=Cache)
 # - downloads/kept/ - Favorited external tracks (always permanent)
-DOWNLOAD_PATH=./downloads
+Library__DownloadPath=./downloads
 
 # ===== SQUIDWTF CONFIGURATION =====
 # Different quality options for SquidWTF. Only FLAC supported right now

allstarr/Program.cs

@@ -626,6 +626,17 @@ builder.Services.AddCors(options =>
 
 var app = builder.Build();
 
+// Migrate old .env file format on startup
+try
+{
+    var migrationService = new EnvMigrationService(app.Services.GetRequiredService<ILogger<EnvMigrationService>>());
+    migrationService.MigrateEnvFile();
+}
+catch (Exception ex)
+{
+    app.Logger.LogWarning(ex, "Failed to run .env migration");
+}
+
 // Configure the HTTP request pipeline.
 app.UseExceptionHandler(_ => { }); // Global exception handler
 

allstarr/Services/Common/CacheCleanupService.cs

@@ -67,7 +67,7 @@ public class CacheCleanupService : BackgroundService
     private async Task CleanupOldCachedFilesAsync(CancellationToken cancellationToken)
     {
         // Get the actual cache path used by download services
-        var downloadPath = _configuration["DOWNLOAD_PATH"] ?? "downloads";
+        var downloadPath = _configuration["Library:DownloadPath"] ?? "downloads";
         var cachePath = Path.Combine(downloadPath, "cache");
 
         if (!Directory.Exists(cachePath))

allstarr/Services/Common/EnvMigrationService.cs

@@ -0,0 +1,59 @@
+namespace allstarr.Services.Common;
+
+/// <summary>
+/// Service that runs on startup to migrate old .env file format to new format
+/// </summary>
+public class EnvMigrationService
+{
+    private readonly ILogger<EnvMigrationService> _logger;
+    private readonly string _envFilePath;
+
+    public EnvMigrationService(ILogger<EnvMigrationService> logger)
+    {
+        _logger = logger;
+        _envFilePath = Path.Combine(Directory.GetCurrentDirectory(), ".env");
+    }
+
+    public void MigrateEnvFile()
+    {
+        if (!File.Exists(_envFilePath))
+        {
+            _logger.LogDebug("No .env file found, skipping migration");
+            return;
+        }
+
+        try
+        {
+            var lines = File.ReadAllLines(_envFilePath);
+            var modified = false;
+
+            for (int i = 0; i < lines.Length; i++)
+            {
+                var line = lines[i].Trim();
+                
+                // Skip comments and empty lines
+                if (string.IsNullOrWhiteSpace(line) || line.StartsWith("#"))
+                    continue;
+
+                // Migrate DOWNLOAD_PATH to Library__DownloadPath
+                if (line.StartsWith("DOWNLOAD_PATH="))
+                {
+                    var value = line.Substring("DOWNLOAD_PATH=".Length);
+                    lines[i] = $"Library__DownloadPath={value}";
+                    modified = true;
+                    _logger.LogInformation("Migrated DOWNLOAD_PATH to Library__DownloadPath in .env file");
+                }
+            }
+
+            if (modified)
+            {
+                File.WriteAllLines(_envFilePath, lines);
+                _logger.LogInformation("✅ .env file migration completed successfully");
+            }
+        }
+        catch (Exception ex)
+        {
+            _logger.LogWarning(ex, "Failed to migrate .env file - please manually update DOWNLOAD_PATH to Library__DownloadPath");
+        }
+    }
+}