Explore a read-only inspector for retained Workflow Workspaces #444

Placeholder

Workflow runs retain a logical Workspace and immutable Workspace roots over
time, but there is no user-facing way to inspect the files represented by that
history. We will eventually need a separate inspector that can show the
contents of a retained Workspace at a selected point without executing or
advancing the workflow.

Boundary

The inspector is separate from workflow execution and lifecycle control. It is
read-only and reaches retained state through a provider-neutral inspection
boundary rather than exposing SQLite or DOFS as the public interface.

Inspection must not:

• resume or replay authored execution;
• acquire executor ownership;
• attach a mutable Workspace transaction;
• change retained files, journal history, lifecycle state, or checkpoints; or
• make storage-engine identities part of the public workflow contract.

The retained Workspace root associated with a journal checkpoint is the
historical state being inspected.

Intentionally unsettled

This issue does not yet choose:

• a CLI, TUI, web interface, library API, or combination of them;
• command names, navigation, rendering, or path-selection UX;
• whether diffing, export, previews, or richer metadata belong in the first
  version; or
• package and process boundaries beyond keeping inspection non-authoritative
  and separate from execution.

Those choices should be designed from concrete inspection workflows before the
issue becomes an implementation story.

Related work

• Add workflow inspection, cancellation, suspension, and deletion #367 owns workflow history and lifecycle inspection, including the mapping
  from retained events to logical Workspace versions.
• This issue concerns viewing the Workspace state those versions identify, not
  adding another execution or lifecycle command by implication.