Implement file-based error logging for all OSes

- Add NLog.Extensions.Logging package for cross-platform file logging
- Configure NLog with separate error and all logs files
- Add log rotation and archiving (10MB files, 7 error archives, 3 all archives)
- Update Program.cs to use NLog provider
- Add logs/ directory to .gitignore
- Ensure NLog.config is copied to output directory

Fixes #114

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: konard

csharp/TraderBot/.gitignore

@@ -1,3 +1,4 @@
 appsettings.json
 log.txt
-log.*.txt
+log.*.txt
+logs/

csharp/TraderBot/NLog.config

@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
+      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+
+  <targets>
+    <!-- File target for errors and above -->
+    <target xsi:type="File" 
+            name="errorFile"
+            fileName="${basedir}/logs/errors-${shortdate}.log"
+            archiveFileName="${basedir}/logs/archived/errors-{#}.log"
+            archiveAboveSize="10485760"
+            archiveNumbering="Rolling"
+            maxArchiveFiles="7"
+            concurrentWrites="true"
+            keepFileOpen="false"
+            layout="${longdate} ${uppercase:${level}} ${logger} ${message} ${exception:format=tostring}" />
+    
+    <!-- File target for all logs -->
+    <target xsi:type="File" 
+            name="allFile"
+            fileName="${basedir}/logs/all-${shortdate}.log"
+            archiveFileName="${basedir}/logs/archived/all-{#}.log"
+            archiveAboveSize="10485760"
+            archiveNumbering="Rolling"
+            maxArchiveFiles="3"
+            concurrentWrites="true"
+            keepFileOpen="false"
+            layout="${longdate} ${uppercase:${level}} ${logger} ${message} ${exception:format=tostring}" />
+    
+    <!-- Console target for development -->
+    <target xsi:type="Console" 
+            name="console"
+            layout="${time} ${uppercase:${level}} ${message} ${exception:format=tostring}" />
+  </targets>
+
+  <rules>
+    <!-- Log all errors and above to error file -->
+    <logger name="*" minlevel="Error" writeTo="errorFile" />
+    
+    <!-- Log everything to all file -->
+    <logger name="*" minlevel="Info" writeTo="allFile" />
+    
+    <!-- Log to console for development -->
+    <logger name="*" minlevel="Info" writeTo="console" />
+  </rules>
+</nlog>

csharp/TraderBot/Program.cs

@@ -2,11 +2,18 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Configuration.UserSecrets;
+using Microsoft.Extensions.Logging;
 using Tinkoff.InvestApi;
 using TraderBot;
+using NLog.Extensions.Logging;
 
 var builder = Host.CreateDefaultBuilder(args);
 var host = builder
+    .ConfigureLogging(logging =>
+    {
+        logging.ClearProviders();
+        logging.AddNLog();
+    })
     .ConfigureServices((context, services) =>
     {
         services.AddSingleton(_ =>

csharp/TraderBot/TraderBot.csproj

@@ -13,8 +13,15 @@
         <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="9.0.2" />
         <PackageReference Include="Microsoft.Extensions.Hosting" Version="9.0.2" />
         <PackageReference Include="Microsoft.Extensions.Logging" Version="9.0.2" />
+        <PackageReference Include="NLog.Extensions.Logging" Version="5.3.8" />
         <PackageReference Include="Platform.Data.Doublets.Sequences" Version="0.1.1" />
         <PackageReference Include="Tinkoff.InvestApi" Version="0.6.1" />
     </ItemGroup>
 
+    <ItemGroup>
+        <None Update="NLog.config">
+            <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+        </None>
+    </ItemGroup>
+
 </Project>

examples/test_logging.cs

@@ -0,0 +1,30 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using NLog.Extensions.Logging;
+
+// Create minimal host to test logging
+var services = new ServiceCollection();
+services.AddLogging(builder =>
+{
+    builder.ClearProviders();
+    builder.AddNLog();
+});
+
+var serviceProvider = services.BuildServiceProvider();
+var logger = serviceProvider.GetRequiredService<ILogger<Program>>();
+
+// Test different log levels
+logger.LogInformation("This is an information message");
+logger.LogWarning("This is a warning message");
+logger.LogError("This is an error message that should be logged to file");
+
+try
+{
+    throw new Exception("Test exception for logging");
+}
+catch (Exception ex)
+{
+    logger.LogError(ex, "Test exception caught and logged");
+}
+
+Console.WriteLine("Logging test completed. Check the logs directory for files.");