UX: Add onboarding guidance after workspace initialization

[frankbria]

Problem

When a new workspace opens with no data, the dashboard doesn't explain the intended sequence of actions. After initialization, the user sees stats cards and QuickActions but no guidance on the next step.

Impact

New users don't know whether to start with PRD, create tasks manually, or execute existing tasks, causing confusion and high friction for first-time use.

Recommendation

After workspace initialization, show a welcome card that explains:

1. Start in PRD page to define requirements
2. Generate tasks from PRD
3. Execute tasks with the AI agent
4. View proof gates to verify quality

Include a 'Get Started →' button linking to /prd. Card dismisses on first navigation.

Acceptance Criteria

• Welcome card appears after init when no PRD/tasks exist
• Card explains 4-step pipeline visually
• CTA links to /prd page
• Card is dismissible and doesn't reappear
• Doesn't appear if workspace already has data

Affected Components

web-ui/src/app/page.tsx, web-ui/src/components/workspace/WorkspaceHeader.tsx

[traycerai]

Warning

Something went wrong while processing your request.

Reference ID: 379c3b28-5795-4f02-b057-d668f4cbd2db

Please try again or contact support if the issue persists, referencing this ID.