speckit-brownfield-migratelisted

# Migrate Existing Features Reverse-engineer spec-kit artifacts (spec.md, plan.md, tasks.md) for features that were built before spec-kit was adopted. This brings existing work into the SDD workflow so teams can track, refine, and extend features using spec-kit commands. ## User Input ```text $ARGUMENTS ``` You **MUST** consider the user input before proceeding (if not empty). The user may specify a feature or module to migrate (e.g., "auth system", "payments module"), a branch name, or "all" to migrate everything. ## Prerequisites 1. Verify a spec-kit project exists by checking for `.specify/` directory 2. Verify git is available and the project is a git repository 3. Verify the project has existing source code to migrate (not an empty project) 4. Verify constitution exists (recommend running `/speckit.brownfield.bootstrap` first if missing) ## Outline 1. **Identify migration targets**: Determine what to migrate based on user input: | Input | Action | |-------|--------| | Specific feature name | Locate the feature in the codebase by searching for related files, modules, or directories | | Specific branch name | Analyze the branch's commits and changed files to identify the feature scope | | Module path | Treat the entire module as a single feature to migrate | | `all` | List all identifiable features and let the user select which to migrate | | No input | Show a list of detected features and ask the user to pick one | 2. **Detect feature bounda