Scope and build a freelancer client-portal SaaS MVP

Build Clientflow, a subscription SaaS web app for solo freelancers and small agencies of 1-5 people. This is the full v1 — build the real data model and working flows, not placeholder screens.

Data model:
- User: id, name, email, role (owner or team_member), avatar_url.
- Client: id, name, company, email, phone, notes, owner_id (references User).
- Project: id, client_id (references Client), title, status (active, on_hold, or completed), start_date, due_date, budget.
- Task: id, project_id (references Project), title, is_done, due_date.
- Invoice: id, project_id (references Project), invoice_number, amount, status (draft, sent, paid, or overdue), due_date, line_items (JSON).
- Comment: id, project_id (references Project), author_id (references User), body, created_at — for client-visible project updates.

Screens and flows:
1. Sign up and log in with email plus Google OAuth.
2. Dashboard: active projects, overdue invoices, and tasks due this week at a glance.
3. Clients list, linking to a client detail page showing all their projects and invoice history.
4. Project detail page: task checklist, a comment thread the client can see, and a 'Create invoice' action.
5. Invoice view: line items, status, and a 'mark as paid' toggle.
6. Billing and settings page listing these subscription tiers: Solo ($15/mo, 1 user), Team ($45/mo, up to 5 users), with a Stripe checkout stub.

Constraints:
- Use Lovable's native Supabase integration for auth (email plus Google) and the database — do not fake data in local component state.
- Row-level security: a User can only see the Clients, Projects, and Invoices where owner_id matches their own auth.uid().
- Primary brand color: #5B4CFF (indigo). Keep the UI calm and unopinionated — this is a tool freelancers show to their own clients.
- Do not build the real Stripe integration yet — a visual checkout screen with a disabled 'connect Stripe' button is enough for this pass.