[feature/openrouter-provider] Add OpenRouter provider support and integrate new models

- Updated README.md to include OpenRouter as a supported provider and its configuration details.
- Added `OPENROUTER_API_KEY` to environment variable configuration.
- Introduced OpenRouter-specific models in `internal/llm/models/openrouter.go` with mappings to existing cost and token configurations.
- Updated `internal/config/config.go` to set default models for OpenRouter agents.
- Extended `opencode-schema.json` to include OpenRouter models in the schema definitions.
- Refactored model IDs and names to align with OpenRouter naming conventions.

Author: isaac-scarrott

README.md

@@ -11,7 +11,7 @@ OpenCode is a Go-based CLI application that brings AI assistance to your termina
 ## Features
 
 - **Interactive TUI**: Built with [Bubble Tea](https://github.com/charmbracelet/bubbletea) for a smooth terminal experience
-- **Multiple AI Providers**: Support for OpenAI, Anthropic Claude, Google Gemini, AWS Bedrock, Groq, and Azure OpenAI
+- **Multiple AI Providers**: Support for OpenAI, Anthropic Claude, Google Gemini, AWS Bedrock, Groq, Azure OpenAI, and OpenRouter
 - **Session Management**: Save and manage multiple conversation sessions
 - **Tool Integration**: AI can execute commands, search files, and modify code
 - **Vim-like Editor**: Integrated editor with text input capabilities
@@ -97,8 +97,12 @@ You can configure OpenCode using environment variables:
       "disabled": false
     },
     "groq": {
-        "apiKey": "your-api-key",
-        "disabled": false
+      "apiKey": "your-api-key",
+      "disabled": false
+    },
+    "openrouter": {
+      "apiKey": "your-api-key",
+      "disabled": false
     }
   },
   "agents": {

internal/config/config.go

@@ -270,9 +270,9 @@ func setProviderDefaults() {
 	// OpenRouter configuration
 	if apiKey := os.Getenv("OPENROUTER_API_KEY"); apiKey != "" {
 		viper.SetDefault("providers.openrouter.apiKey", apiKey)
-		viper.SetDefault("agents.coder.model", models.GPT41)
-		viper.SetDefault("agents.task.model", models.GPT41Mini)
-		viper.SetDefault("agents.title.model", models.GPT41Mini)
+		viper.SetDefault("agents.coder.model", models.OpenRouterGPT41)
+		viper.SetDefault("agents.task.model", models.OpenRouterGPT41Mini)
+		viper.SetDefault("agents.title.model", models.OpenRouterGPT41Mini)
 		return
 	}
 
@@ -596,12 +596,12 @@ func setDefaultModelForAgent(agent AgentName) bool {
 
 		switch agent {
 		case AgentTitle:
-			model = models.GPT41Mini
+			model = models.OpenRouterGPT41Mini
 			maxTokens = 80
 		case AgentTask:
-			model = models.GPT41Mini
+			model = models.OpenRouterGPT41Mini
 		default:
-			model = models.GPT41
+			model = models.OpenRouterGPT41
 		}
 
 		// Check if model supports reasoning