PR-07c Asset Details and Form Lifecycle

Domain owner: docs/studio

Briefing

Refactor the selected-asset details side so the details host and its internal sections/forms subscribe only to the state they need.

This slice explicitly covers the problem called out in the current direction:

the selected-asset details host must not own all redraws;
each internal section/form must update from events instead of full details rebuilds.

Make the details area componentized, lifecycle-aware, and event-driven.

After this PR:

summary/actions, runtime contract, inputs/preview, diagnostics, and mutation-preview sections can update independently;
details load state, ready state, and error state are event-driven;
local form interactions such as preload toggles or preview selection do not rebuild unrelated details content;
internal controls subscribe only while mounted.
the details-section and form-subscription patterns become reusable Studio workspace primitives where appropriate.

extract the details host into dedicated controls
split details content into lifecycle-aware sections
extract reusable section-host and form-event patterns when they are not asset-specific
define details events for:
- details loading started
- details ready
- details failed
- local summary patch applied
- preview input changed
- preview zoom changed
- mutation preview state changed
route details-local form actions through the workspace bus instead of root-owned imperative redraw

no navigator refactor in this slice
no shell activity redesign in this slice
no cross-workspace form framework extraction unless needed by the Assets details controls

Introduce a dedicated details host control with lifecycle-managed subscriptions.
Extract stable details sections into separate controls.
Move details load and error transitions to typed events.
Route details-local interactions through narrow events and local state holders.
Remove root-level details reconstruction for interactions that affect only one section.

the selected-asset details view is no longer rebuilt as one large region for section-local changes
forms and preview controls update independently
details-ready and details-error transitions are observable through typed events
details-local subscriptions are owned by the mounted controls, not the workspace root
changing one local control does not force unrelated details sections to rerender
reusable details/form lifecycle patterns are available for future Studio workspaces

unit tests for details lifecycle event flow
unit tests for section-local updates
unit tests for preload-toggle or equivalent form patch behavior
UI smoke validation for selection, details loading, preview interaction, and diagnostics visibility

prometeu-studio/src/main/java/p/studio/workspaces/assets/AssetWorkspace.java
new details controls under prometeu-studio/src/main/java/p/studio/workspaces/assets/...
prometeu-studio/src/main/java/p/studio/events/...
tests for details load state and section-local updates