PR-07e Assets Refactor Cleanup and Regression Coverage

Domain owner: docs/studio

Briefing

Consolidate the refactor by removing obsolete redraw-heavy code paths, tightening naming, and locking the event-driven behavior with tests.

Finish the corrective refactor so the codebase does not drift back toward monolithic render ownership.

After this PR:

obsolete redraw-request and monolithic render helpers are removed;
remaining component boundaries are clearer and easier to maintain;
tests guard lifecycle, event routing, and selective-update behavior;
the workspace code is organized around durable responsibilities rather than incremental leftovers.
the resulting framework is left in a shape that other Studio workspaces can adopt directly.

remove dead or transitional redraw-oriented code
rename classes/events where the old naming reflects the wrong direction
tighten package structure for navigator, details, and orchestration code
make reusable framework pieces visible and discoverable to future workspace implementations
add regression coverage for:
- lifecycle subscription hygiene
- selection propagation
- row patch propagation
- details-local updates
- structural sync boundaries
update Studio learn/spec material if the refactor exposes terminology drift

no new user-facing asset features in this slice
no speculative refactor outside the Assets workspace and its direct event contracts

Remove compatibility layers that existed only to bridge from the old refresh-heavy implementation.
Normalize class and event naming around lifecycle and event-driven ownership.
Reorganize tests to reflect component boundaries instead of one giant workspace class.
Update documentation to reflect the stabilized architecture.

the refactored Assets workspace no longer depends on redraw-request events as a primary mechanism
code ownership is split along navigator, details, and orchestration boundaries
lifecycle and event-driven behavior are covered by focused tests
the remaining AssetWorkspace root is materially smaller and primarily compositional
the reusable framework surface is clear enough for other workspaces to consume instead of cloning Assets internals

full unit-test pass for asset-workspace packages
targeted regression tests for mount/unmount lifecycle safety
targeted regression tests proving that local updates stay local unless structural sync is requested