chore: add debugger config to run standalone mcp

[nbouliol]

Definition of Done

General

• Write an explicit title for the Pull Request, following Conventional Commits specification
• Test manually the implemented changes
• Validate the code quality (indentation, syntax, style, simplicity, readability)

Security

• Consider the security impact of the changes made

Note

Add VSCode debugger config to run the standalone MCP server

Adds a launch.json debug configuration that runs dist/cli.js from packages/mcp-server with source maps and required FOREST_* environment variables. Also adds a tasks.json build-all task that runs yarn build as a pre-launch step.

^{Macroscope summarized 4613c3c.}