EPIC: Workspace experience

Programme: #1

Own the persistent workspace as the primary product object: home/navigation, synchronized Personal/Original/Evidence views, trusted task/approval surfaces, command palette, semantic selection and accessibility.

## Child issues
- [ ] #37 WS-01 — Persistent workspace store and navigation
- [ ] #38 WS-02 — Personal, Original and Evidence views
- [ ] #39 WS-03 — Trusted control surfaces and task centre
- [ ] #40 WS-04 — Command palette, semantic selection and accessibility

## Cross-cutting gates
Workspace survives chat/model/provider changes, trusted controls cannot be spoofed, deterministic interactions work without inference, and core flows are keyboard/assistive-tech usable.

Start with child issues #37–#40, covering the persistent workspace store, navigation, synchronized views, trusted controls, task centre, command palette, semantic selection and accessibility. Read each child issue before choosing a bounded task. Done requires the listed cross-cutting gates: workspace persistence across chat/model/provider changes, non-spoofable controls, deterministic interactions without inference, and keyboard/assistive-tech usability.

Written by the indexing model from the issue text.