Function createUxpConnection

Establishes a connection to Photoshop via CDP. Uses the fake-plugin from uxp-devtools-common by default.

Configuration via environment variables:

• PHOTOSHOP_MCP_PLUGIN_PATH: Path to the UXP plugin directory
• PHOTOSHOP_MCP_PLUGIN_ID: Plugin ID from manifest.json

The connection is cached and reused for subsequent calls.