slice 1.0.6: POST /demo/start — seed workspace from starter template

[sausi-7]

Phase 1.0 demo slice · Difficulty: D1 (good first issue)

Scope

POST /demo/start copies packages/templates/demo-starter/ into workspace/demo/, returns {ready: true, preview_port: 4300}. Idempotent — re-running wipes and re-seeds.

Acceptance criteria

• Endpoint exists and returns 200.
• Workspace contents match the starter after the call.
• Integration test against a temp workspace dir.

[Gui11SB7]

I can take it. Should I create a router /demo?