Normalize Clerk org admin role to admin; improve project creation fallback

Added a role-mapping function that normalised Clerk membership roles (for example, 'org:admin' or namespaced 'owner' roles) to the internal 'admin' or 'member' values so membership permissions are interpreted consistently.auth
Updated organization membership creation and update handlers to use the new role mapping so users with namespaced admin roles are treated as admins in SuprLogs.backend
Added an automated test to verify membership.created events correctly map namespaced Clerk admin roles to the internal 'admin' role.backend
Updated the web project creation flow to fall back to creating the project under the user's personal account if creating under the selected organization is forbidden, reducing hard failures during project creation.frontend

Added backlog items outlining planned UX and platform improvements (explicit owner selection during project creation, multi-organization membership model, and billing context separation).