feat: add checksum-based MCP type validation and auto-regeneration

Implement automatic detection of MCP tool changes with FNV-1a hash-based
checksum validation. Types now regenerate only when tools change, improving
startup performance and ensuring type definitions stay synchronized.

Features:
- Checksum calculation for tool signatures (namespace + input schema)
- Automatic regeneration when MCP tools change
- Skip regeneration when tools unchanged (faster startup)
- Configurable type distribution via CODEMODE_TYPE_COPY_PATH env var
- Persistent checksum storage in generated/mcp.d.ts.checksum

Changes:
- Update @modelcontextprotocol/sdk 0.4.0 → 1.18.2 (protocol compatibility)
- Add configurable CodeGenOptions.copyToPath parameter
- Enhance agent instructions to read mcp://types/declarations resource
- Improve MCP server connection logging and debugging

BREAKING CHANGE: Server constructor updated for MCP SDK v1.18.2

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

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

Author: danieliser

CHANGELOG.md

@@ -0,0 +1,52 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+- Checksum-based validation for MCP tool type declarations
+  - FNV-1a hash calculation of tool signatures (namespace + input schema)
+  - Automatic detection of tool list changes on server initialization
+  - Checksum persistence to `generated/mcp.d.ts.checksum`
+  - Auto-regeneration of TypeScript declarations when tools change
+  - Skip regeneration when tools unchanged (faster startup)
+- Configurable type declaration distribution
+  - Optional `copyToPath` configuration for CodeGenService
+  - Environment variable `CODEMODE_TYPE_COPY_PATH` (comma-separated paths)
+  - Supports copying generated types to multiple destinations
+  - Ensures type definitions available across project structure
+- Enhanced MCP configuration logging
+  - Debug output for server discovery and configuration
+  - Tool discovery progress indicators
+  - Connection status and tool count reporting
+
+### Changed
+- Updated `@modelcontextprotocol/sdk` from 0.4.0 to 1.18.2
+  - Fixed protocol version compatibility issues
+  - Updated Server constructor for new API
+  - Enabled connection to MCP servers using 2025-06-18 protocol
+- Improved `execute_code` tool description
+  - Added **IMPORTANT** directive for agents
+  - Explicit instruction to read `mcp://types/declarations` resource
+  - Ensures type-safe code generation with current tool definitions
+
+### Fixed
+- MCP type declarations now automatically regenerate when new servers connect
+- Protocol version compatibility with newer MCP servers (2025-06-18 protocol)
+- TypeScript declarations stay synchronized with available MCP tools across all connected servers
+
+## [0.1.0] - 2025-10-02
+
+### Added
+- Initial release with MCP integration
+- Multi-runtime code execution (QuickJS, Bun, Deno, isolated-vm, E2B)
+- TypeScript declaration generation from MCP tool schemas
+- MCP Resources and Prompts support
+- Two-pass execution for async MCP tool calls in sync runtimes
+
+[Unreleased]: https://github.com/danieliser/codemode-unified/compare/v0.1.0...HEAD
+[0.1.0]: https://github.com/danieliser/codemode-unified/releases/tag/v0.1.0