Add the workspace page at /workspace with two modes:
- Project selector (no ?project param): grid of project cards to choose from
- Workspace view (?project=<id>): project detail with tabbed sections for
Tasks, Agent Sessions, and Project Settings
Also creates the runner-jobs API client for fetching workspace-level
runner job data.
Refs #468
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
