feat: Enhanced Gemini MCP server for large-scale code analysis

Major improvements:
- Default model set to Gemini 1.5 Pro (more reliable than 2.5 Preview)
- Added analyze_code tool for processing large files and codebases
- Support for 1M token context window
- File reading capabilities for automatic code ingestion
- Enhanced documentation with usage examples
- Added USAGE.md guide for Claude Code users

Changes:
- Updated default model configuration with fallback note
- Increased default max_tokens to 8192 for better responses
- Added CodeAnalysisRequest model for structured code analysis
- Implemented file reading with proper error handling
- Added token estimation (~4 chars per token)
- Created comprehensive test suite for new features

This update makes the server ideal for handling large files that exceed
Claude's token limits, enabling seamless handoff to Gemini for extended
analysis and thinking.

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

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

USAGE.md

@@ -0,0 +1,80 @@
+# Usage Guide for Claude Code Users
+
+## Quick Start
+
+When using this Gemini MCP server from Claude Code, you can interact with it naturally. Here are the most common patterns:
+
+## Basic Chat
+
+Simply ask Claude to use the Gemini tool:
+
+```
+Ask Gemini: What are the key differences between async and sync programming in Python?
+```
+
+## Analyzing Large Files
+
+When Claude can't handle a large file due to token limits:
+
+```
+Use Gemini to analyze this file: /path/to/very/large/file.py
+Question: What are the main components and their relationships?
+```
+
+## Multiple File Analysis
+
+For architectural understanding across files:
+
+```
+Use Gemini to analyze these files together:
+- /src/models/user.py
+- /src/controllers/auth.py
+- /src/services/database.py
+Question: How do these components work together for user authentication?
+```
+
+## Code Review
+
+For detailed code review:
+
+```
+Have Gemini review this code:
+[paste your code here]
+Question: What improvements would you suggest for performance and maintainability?
+```
+
+## Extended Thinking
+
+When you need deep analysis:
+
+```
+Use Gemini for extended analysis of /path/to/complex/algorithm.py
+Question: Can you trace through the algorithm step by step and identify any edge cases?
+```
+
+## Model Selection
+
+To use a specific model (like 2.5 Pro Preview):
+
+```
+Use Gemini with model gemini-2.5-pro-preview-06-05 to analyze...
+```
+
+## Tips
+
+1. **File Paths**: Always use absolute paths when specifying files
+2. **Questions**: Be specific about what you want to know
+3. **Temperature**: Lower values (0.1-0.3) for factual analysis, higher (0.7-0.9) for creative tasks
+4. **Context**: Gemini can handle up to 1M tokens (~4M characters)
+
+## Common Commands
+
+- "Use Gemini to analyze..."
+- "Ask Gemini about..."
+- "Have Gemini review..."
+- "Get Gemini's opinion on..."
+- "Use Gemini for extended thinking about..."
+
+## Integration with Claude
+
+The MCP server integrates seamlessly with Claude. When Claude recognizes you want to use Gemini (through phrases like "use gemini", "ask gemini", etc.), it will automatically invoke the appropriate tool with the right parameters.