Creates Workspace, WorkspaceMember, WorkspaceInvitation, Link,
LinkVariant, Click (append-only), Plan, and Domain Eloquent models with
correct relationships. Updates User model with SoftDeletes, ULID
auto-generation on create, guarded/casts, and workspace relationships.
Fixes ProfileTest assertion to match SoftDeletes behavior on User.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
boban