[MVP] Self-service workspace registration

Allow new customers to sign up for GanttForce on their own without needing the Platform Superadmin to create their workspace manually. A public landing page and onboarding flow takes a new user from sign-up to a working workspace in minutes.

Why this matters

The current onboarding requires the Platform Superadmin to manually create each workspace. This makes GanttForce unsuitable for self-serve growth — every new customer is gated on a manual step. Self-service registration is a fundamental requirement for scaling beyond a small number of managed clients.

How it works

A public-facing landing page explains GanttForce's features and pricing. Clicking "Get started" or "Sign up free" opens a registration form where the user enters their name, email, company name, and password. After verifying their email, their workspace is automatically provisioned and they are taken through a brief onboarding flow: set up their first project, invite a colleague, and explore the Gantt. New workspaces start on the Free plan. An upgrade path to Pro is presented within the application when limits are approaching.