feat: Add project's root as an environment variable to support dev containers

[leoneparise]

Motivation

• MCPs in Cursor only runs on host machine and doesn't have access to dev container paths.
• All terminal commands from AI agent runs in dev container.
• All MCP commands requires a project root parameter. The AI agent try to infer from a pwd command and gives the wrong path.

Proposed Solution

Create an environment variable in MCP config to map the project root path in the host machine and make projectRoot parameter optional. As a workaround I created a root_path.mcp with the following content:

# Root path for task master MCP

Use root path as `<root_path>` for task master rcp calls.

If the change is too complex please update the documentation and include the workaround for dev containers environments.

[eyaltoledano]

we could add a path to the config, shouldn’t be too hardcore to do.

[eyaltoledano]

I'm going to table this for a little bit because i'm about to introduce a breaking change with .taskmasterconfig -- will revisit this after that's out or see if i can weasel it into the PR at the same time if it's not too much trouble

I will say project roots have been a lynchpin so far so lol