feat(isolation): introduce Git worktree isolation and MCP server

[moisgobg]

Description

This PR introduces an MCP (Model Context Protocol) server to manage isolated Git worktrees and integrates this isolation mechanism into the core Conductor commands.

Changes

1. MCP Server for Worktree Management:

   • Bootstraps a new Node.js MCP server in src/ to expose Git worktree operations.
   • Provides create_worktree, delete_worktree, and list_worktrees tools.
   • Includes full unit test coverage for the Git isolation logic (src/isolation.test.ts).
   • Configures gemini-extension.json to register the conductor MCP server.

2. Integration into Conductor Commands:

   • implement: Checks for existing worktrees or creates a new one using the create_worktree tool. Instructs the agent to perform all execution and file reads within this isolated context.
   • review: Detects if an isolated worktree exists for the track being reviewed. Ensures pre-checks (linting, building, testing) and diff analysis run within the context of the worktree. Provides options to discard the isolated work or merge it into the base branch.
   • revert: Integrates awareness of active worktrees, offering pre-merge options like aborting the track (destroying the worktree), rolling back the last commit within the worktree, or rolling back to a checkpoint.