kata-starting-milestones

<objective>
Start a new milestone through unified flow: questioning → research (optional) → requirements → roadmap.

This is the brownfield equivalent of project-new. The project exists, PROJECT.md has history. This command gathers "what's next", updates PROJECT.md, then continues through the full requirements → roadmap cycle.

**Creates/Updates:**
- `.planning/PROJECT.md` — updated with new milestone goals
- `.planning/research/` — domain research (optional, focuses on NEW features)
- `.planning/REQUIREMENTS.md` — scoped requirements for this milestone
- `.planning/ROADMAP.md` — phase structure (continues numbering)
- `.planning/STATE.md` — reset for new milestone

**After this command:** Run `/kata:phase-plan [N]` to start execution.
</objective>

<execution_context>
@./references/questioning.md
@./references/ui-brand.md
@./references/project-template.md
@./references/requirements-template.md
</execution_context>

<context>
Milestone name: $ARGUMENTS (optional - will prompt if not provided)

**Load project context:**
@.planning/PROJECT.md
@.planning/STATE.md
@.planning/MILESTONES.md
@.planning/config.json

**Load milestone context (if exists, from /kata:discuss-milestone):**
@.planning/MILESTONE-CONTEXT.md
</context>

<process>

## Phase 1: Load Context

- Read PROJECT.md (existing project, Validated requirements, decisions)
- Read MILESTONES.md (what shipped previously)
- Read STATE.md (pending todos, blockers)
- Check for MILESTONE-CONTEXT.md (from /kata:discuss-milestone)

## Phase 2: Gather Milestone Goals

**If MILESTONE-CONTEXT.md exists:**
- Use features and scope from discuss-milestone
- Present summary for confirmation

**If no context file:**
- Present what shipped in last milestone
- Ask: "What do you want to build next?"
- Use AskUserQuestion to explore features
- Probe for priorities, constraints, scope

## Phase 3: Determine Milestone Version

- Parse last version from MILESTONES.md
- Suggest next version (v1.0 → v1.1, or v2.0 for major)
- Confirm wi