Support passing prompt to `/plan`

[jerop]

Right now, /plan takes you to a separate plan box. /plan should accept text so you can kick off a plan in a single command.

/plan should accept text, so that plans can be created in one user action.

[rambleraptor]

/assign

[gemini-cli]

👋 @rambleraptor, thanks for your interest in this issue! We're reserving self-assignment for issues that have been marked with the help wanted label. Feel free to check out our list of issues that need attention.