Add Luna.Configuration with TOML-based agent and provider config

Implement configuration system with embedded TOML resources for agent
and provider definitions, custom IConfigurationSource/Provider for
agent and provider options, and DI extension methods. Includes config
models for agents, providers, sessions, and Telegram integration.

Luna.Configuration/Services/Agents/AgentOptionsConfigurationProvider.cs

@@ -0,0 +1,20 @@
+using System.Reflection;
+using Microsoft.Extensions.Configuration;
+
+namespace Luna.Configuration.Services.Agents;
+
+internal class AgentOptionsConfigurationProvider(IEnumerable<AgentOptions> agentOptions) : ConfigurationProvider
+{
+    public override void Load()
+    {
+        foreach (var options in agentOptions)
+        {
+            var keyPrefix = $"Agents:{options.Name}";
+
+            foreach (var property in options.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public))
+            {
+                Data[$"{keyPrefix}:{property.Name}"] = property.GetValue(options)?.ToString();
+            }
+        }
+    }
+}

Luna.Configuration/Services/Agents/AgentOptionsConfigurationSource.cs

@@ -0,0 +1,12 @@
+using Microsoft.Extensions.Configuration;
+
+namespace Luna.Configuration.Services.Agents;
+
+internal class AgentOptionsConfigurationSource(string? searchPath = null)
+    : IConfigurationSource
+{
+    private readonly AgentOptionsProvider optionsProvider = new(searchPath);
+
+    public IConfigurationProvider Build(IConfigurationBuilder builder)
+        => new AgentOptionsConfigurationProvider(optionsProvider.GetAgentOptions());
+}

Luna.Configuration/Services/Agents/AgentOptionsProvider.cs

@@ -0,0 +1,60 @@
+using System.Text.RegularExpressions;
+using Tomlyn;
+
+namespace Luna.Configuration.Services.Agents;
+
+internal sealed class AgentOptionsProvider(string? searchPath = null)
+{
+    private readonly EmbeddedResourceLoader embeddedResourceLoader = new();
+    
+    public IEnumerable<AgentOptions> GetAgentOptions()
+    {
+        return string.IsNullOrWhiteSpace(searchPath)
+            ? GetAgentOptionsFromEmbeddedResources()
+            : GetAgentOptionsFromFiles();
+    }
+
+    private IEnumerable<AgentOptions> GetAgentOptionsFromFiles()
+    {
+        ArgumentException.ThrowIfNullOrEmpty(searchPath);
+
+        var files = Directory.Exists(searchPath)
+            ? Directory.EnumerateFiles(searchPath, "Agent.*.toml")
+            : [];
+        
+        foreach (var file in files)
+        {
+            using var reader = File.OpenText(file);
+            var agentOptions = TomlSerializer.Deserialize<AgentOptions>(reader);
+            
+            yield return agentOptions
+                ?? throw new FormatException($"Invalid agent config file: {file}");
+        }
+    }
+    
+    private IEnumerable<AgentOptions> GetAgentOptionsFromEmbeddedResources()
+    {
+        var resources = embeddedResourceLoader.ListResources("Agent.*.toml");
+        foreach (var resource in resources)
+        {
+            var content = embeddedResourceLoader.LoadAsync(resource).GetAwaiter().GetResult();
+            var agentOptions = TomlSerializer.Deserialize<AgentOptions>(content);
+            
+            yield return agentOptions
+                ?? throw new FormatException($"Invalid agent config embedded resource: {resource}");
+        }
+    }
+}
+
+internal static partial class StringExtensions
+{
+    [GeneratedRegex(@"Agent\.(.+)\.toml", RegexOptions.IgnoreCase | RegexOptions.Compiled)]
+    private static partial Regex AgentNameRegex { get; }
+    
+    extension(string str)
+    {
+        public string ToAgentName() => AgentNameRegex.Match(str) is { Success: true } match
+            ? match.Groups[1].Value
+            : throw new FormatException($"Invalid agent config file name: {str}");
+    }
+}