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>

.gitignore

@@ -1 +1,73 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+# Dependency directories
+node_modules/
+.pnp
+.pnp.js
+
+# Build outputs
+dist/
+dist-ssr/
+build/
+.next/
+out/
+
+# Environment variables
+.env
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Coverage directory used by tools like istanbul
+coverage/
+*.lcov
+.nyc_output/
+
+# Vite
+.vite/
+
+# Testing
+.vitest/
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea/
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?
+
+# OS generated files
+Thumbs.db
+ehthumbs.db
+
+# Temporary files
+*.tmp
+*.temp
+.cache/
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Reference materials (keeping this as requested)
 reference_info/