fix: avoid redeclaring WP-CLI global --user in mcp serve #328

Problem

mcp serve declares --user as a command option while WP-CLI already reserves --user as a global bootstrap option. Registering the command causes a conflicting-global-argument warning before unrelated command output.

Synthetic reproduction

With the adapter active, run:

wp help mcp serve

Expected: command registration emits no global-argument collision warning.

Actual: the command-owned --user synopsis collides with WP-CLI's global option.

Suggested direction

Rely on WP-CLI's global --user context, or rename the command-specific option and preserve documented behavior with a registration-level regression test.

AI Assistance Disclosure

OpenCode, using openai/gpt-5.6-terra, directly orchestrated this report under Chris Huber's authorization.