feat: Introduce a pluggable LLM provider system with token extraction, pricing, and updated setup configuration.

SetupTui.cs

@@ -27,17 +27,93 @@ internal static class SetupTui
 
         AnsiConsole.WriteLine();
 
+        // ── Provider ────────────────────────────────────────────────────
+        var providers = new List<(string Value, string Description)>
+        {
+            ("openrouter", "default, pricing support"),
+            ("groq", "high-speed inference"),
+            ("ollama", "local, no auth required"),
+            ("openai", "official OpenAI API"),
+            ("custom", "generic OpenAI-compatible endpoint")
+        };
+
+        string currentProvider = config.Provider ?? "openrouter";
+        AnsiConsole.MarkupLine($"  Current provider: [cyan]{Markup.Escape(currentProvider)}[/]");
+
+        var selectedProviderChoice = AnsiConsole.Prompt(
+            new SelectionPrompt<(string Value, string Description)>()
+                .Title("  Select a provider:")
+                .UseConverter(p => p.Value + (string.IsNullOrEmpty(p.Description) ? "" : $" [dim]({p.Description})[/]"))
+                .AddChoices(providers));
+
+        config.Provider = selectedProviderChoice.Value;
+
+
+
+
+        if (config.Provider == "custom")
+        {
+            string customEndpoint = AnsiConsole.Prompt(
+                new TextPrompt<string>("  Enter endpoint URL:")
+                    .DefaultValue(config.Endpoint)
+                    .AllowEmpty());
+
+            if (!string.IsNullOrWhiteSpace(customEndpoint))
+            {
+                config.Endpoint = customEndpoint.Trim();
+            }
+        }
+        else
+        {
+            config.Endpoint = config.Provider.ToLowerInvariant() switch
+            {
+                "openrouter" => "https://openrouter.ai/api/v1",
+                "groq" => "https://api.groq.com/openai/v1",
+                "ollama" => "http://localhost:11434/v1",
+                "openai" => "https://api.openai.com/v1",
+                _ => config.Endpoint
+            };
+        }
+
+        AnsiConsole.WriteLine();
+
         // ── Model ─────────────────────────────────────────────────────
         AnsiConsole.MarkupLine($"  Current model: [cyan]{Markup.Escape(config.Model)}[/]");
 
-        var models = new List<(string Value, string Description)>
+        var models = config.Provider.ToLowerInvariant() switch
         {
-            ("qwen/qwen3.5-397b-a17b", "smart, expensive"),
-            ("qwen/qwen3.5-122b-a10b", "faster"),
-            ("qwen/qwen3.5-27b", "fast"),
-            ("qwen/qwen3.5-flash-02-23", "cloud, fast"),
-            ("qwen/qwen3.5-plus-02-15", "cloud, smart"),
-            ("Custom...", "")
+            "groq" => new List<(string Value, string Description)>
+            {
+                ("llama-3.3-70b-versatile", "fast, powerful"),
+                ("llama-3.1-8b-instant", "very fast"),
+                ("mixtral-8x7b-32768", "sparse MoE"),
+                ("gemma2-9b-it", "Google's Gemma"),
+                ("Custom...", "")
+            },
+            "ollama" => new List<(string Value, string Description)>
+            {
+                ("llama3.2", "Meta's Llama 3.2"),
+                ("qwen2.5", "Alibaba Qwen"),
+                ("mistral", "Mistral AI"),
+                ("codellama", "code-focused"),
+                ("Custom...", "")
+            },
+            "openai" => new List<(string Value, string Description)>
+            {
+                ("gpt-4o", "most capable"),
+                ("gpt-4o-mini", "fast, affordable"),
+                ("o1-preview", "reasoning model"),
+                ("Custom...", "")
+            },
+            _ => new List<(string Value, string Description)>
+            {
+                ("qwen/qwen3.5-397b-a17b", "smart, expensive"),
+                ("qwen/qwen3.5-122b-a10b", "faster"),
+                ("qwen/qwen3.5-27b", "fast"),
+                ("qwen/qwen3.5-flash-02-23", "cloud, fast"),
+                ("qwen/qwen3.5-plus-02-15", "cloud, smart"),
+                ("Custom...", "")
+            }
         };
 
         string selectedModel = AnsiConsole.Prompt(