Add Pi Research Agent package

Autonomous research agent with web search, source analysis, and report synthesis.
Built on Pi agent core. Available as CLI, programmatic API, and MCP server.

Features:
- 4 built-in tools: web_search, read_url, save_note, synthesize_report
- CLI with TUI and print modes
- Programmatic API via ResearchAgent class
- MCP server with 3 tools: research, quick_search, read_url
- Skills system for custom research behavior
- Automatic .env file loading for API keys
- Configurable max turns, output formats (markdown/JSON/bullet)
- Automatic report saving to research-output/

packages/research-agent/.env.example

@@ -0,0 +1,11 @@
+# Tavily API key for web search
+# Get your key at: https://tavily.com/
+TAVILY_API_KEY=***
+
+# OpenRouter API key for LLM
+# Get your key at: https://openrouter.ai/
+OPENROUTER_API_KEY=***
+
+# Optional: Override default model (minimax/minimax-m3)
+# Examples: openai/gpt-4o, anthropic/claude-3.5-sonnet, google/gemini-pro-1.5
+# LLM_MODEL=minimax/minimax-m3