Implement complete InferenceProvider system with OpenRouter integration

## Features
- 🔧 InferenceProvider interface with pluggable architecture
- 🔑 OpenRouter API key and OAuth PKCE authentication providers
- 🛠️ Tool calling support with automatic agent loop execution
- 📱 Interactive test UI with model selection and chat interface
- 🎯 Provider-level filtering to tool-capable models only
- ⚛️ React context with proper state management for UI reactivity

## Components
- Core types and interfaces in src/types/inference.ts
- OpenRouter client with shared utilities for both auth methods
- Two separate providers (composition over inheritance):
  - OpenRouterApiProvider for API key authentication
  - OpenRouterOAuthProvider for OAuth PKCE flow
- React InferenceContext with useInference hook
- Interactive test UI with tool calling demonstration
- OAuth callback routing with proper namespacing

## Tool Calling
- 3 test tools: weather, calculator, time
- Automatic tool execution and agent loop
- Visual tool call display with arguments and results
- Error handling for malformed tool calls

## Bug Fixes
- Fixed model selection UI reactivity issue
- Fixed OAuth popup race condition causing "cancelled" errors
- Proper cleanup of event listeners and intervals

## Documentation
- Comprehensive interface design document
- Implementation strategy and key design decisions
- Testing approach and security considerations

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

Co-Authored-By: Claude <noreply@anthropic.com>

src/App.tsx

@@ -0,0 +1,32 @@
+import React from 'react'
+import { InferenceProvider } from '@/contexts/InferenceContext'
+import { InferenceTest } from '@/components/InferenceTest'
+import { OAuthCallback } from '@/components/OAuthCallback'
+
+function App() {
+  // Simple routing based on pathname
+  const pathname = window.location.pathname;
+  const isInferenceOAuthCallback = pathname === '/oauth/inference/callback';
+  const isMcpOAuthCallback = pathname.startsWith('/oauth/mcp/');
+
+  if (isInferenceOAuthCallback) {
+    return <OAuthCallback type="inference" />;
+  }
+
+  if (isMcpOAuthCallback) {
+    // Extract server identifier from path like /oauth/mcp/server123/callback
+    const serverMatch = pathname.match(/^\/oauth\/mcp\/([^\/]+)\/callback$/);
+    const serverId = serverMatch?.[1];
+    return <OAuthCallback type="mcp" serverId={serverId} />;
+  }
+
+  return (
+    <InferenceProvider>
+      <div className="min-h-screen bg-gray-100 dark:bg-gray-900">
+        <InferenceTest />
+      </div>
+    </InferenceProvider>
+  )
+}
+
+export default App