Removes the Workspace section from the Sessions filter dropdown.
Final dropdown is All + Project. Simplifies the filter discriminated
union (drops the "workspace" variant), the predicate, and the
hook-derived option list. Workspace mapping is still used internally
to map session cwd to project for the Project filter and for hiding
unmapped agents.
E2E journey simplified — the workspace-filter step is gone, including
its brittle accessible-name regex.
670e6a6fdd