CLI: Add Telex commands

[youknowriad]

(More context coming soon)

This PR integrates Telex - an AI-assisted WordPress block authoring environment - directly into the Studio CLI. Users can now generate and install WordPress blocks using natural language prompts, with blocks automatically installed to their local Studio sites.

New Commands

studio telex block [prompt]

Generate a WordPress block using AI and install it to the current site.

# Interactive mode
studio telex block

# Direct prompt
studio telex block "testimonial carousel"

# Specify site path
studio telex block "hero section" --path ~/sites/mysite

The command:

1. Authenticates with WordPress.com (uses existing Studio auth)
2. Generates a complete block using Telex AI
3. Waits for the block to build
4. Installs the block to your local Studio site
5. Provides activation instructions

studio telex install [project-id]

Install an existing block from Telex to your local site.

  # Interactive mode (prompts for URL or ID)
  studio telex install

  # Install by ID
  studio telex install v1.abc123

  # Install by URL
  studio telex install https://telex.automattic.ai/projects/v1.abc123

Configuration:

Developers can override the Telex API URL via the STUDIO_TELEX_URL environment variable for local development:

export STUDIO_TELEX_URL=http://telex.localhost:8000/