/brainstorm-plan

Create a comprehensive implementation plan from a design doc or conversation context

# Plan: Design to Implementation

Create a comprehensive, detailed implementation plan that a skilled but zero-context engineer could follow.

## Input Source

$ARGUMENTS

If an argument was provided, read that file as the design doc.
If no argument, use the conversation context (assume a design was just discussed via /brainstorm or otherwise).

If neither exists, ask the user: "What feature or design would you like me to create an implementation plan for?"

## Target Audience

Write this plan for an engineer who:
- Is skilled at coding but has **zero context** for this codebase
- Has **que...