[BUG] Custom buildable models lack hover and selection outlines during employee assignment

[ifBars]

Summary

Custom buildable/station models can be selectable during employee assignment without showing the native white hover or selected outline.

This is visible with MoreDrugs' custom tablet press. Players reasonably interpret the missing outline as the station being unavailable or incompatible with the selected employee.

Environment

• Game version: reported on 0.4.6f13
• Consumer mod: MoreDrugs / Drug Expansion
• Example station: custom tablet press
• Employee type: Handler (same assignment role as the native brick press)
• Runtime: reported on the regular/default game branch; Mono parity has not yet been confirmed
• Exact S1API and MoreDrugs versions from the original reports are unknown, though reporters were advised to update both before retesting

Steps to reproduce

1. Install current compatible versions of S1API and MoreDrugs.
2. Place a custom tablet press.
3. Start employee assignment for a Handler.
4. Hover the assignment cursor over the tablet press.
5. Click the tablet press to select it.

Expected behavior

The tablet press model should show the same white hover and selected outlines as a native assignable station such as the brick press.

The assignment UI should clearly communicate that the station is a valid target and remains selected.

Actual behavior

The custom tablet press shows no white outline while hovered or selected.

In confirmed reports, clicking the press still changes the assignment count (for example, 0/3 to 1/3) and pressing E confirms the assignment. One earlier report described the press as not clickable, but after updating the mod/API stack the player confirmed that the non-highlighted click-and-confirm flow worked.

The reproducible defect is therefore the missing visual hover/selection feedback; assignment failure may have been version or installation related.

Why this matters

The interaction is functionally hidden. Multiple players concluded that Handlers could not operate the tablet press because the normal native selection feedback was absent.

Acceptance criteria

• Custom assignable buildable/station models receive the native hover outline during employee assignment.
• The selected station retains the native selected outline until confirmed or deselected.
• Assignment behavior remains unchanged.
• The fix works for custom station renderers without requiring each consumer mod to recreate native outline wiring.
• Mono and IL2CPP behavior are validated separately.

Additional context

This may share underlying renderer/highlight composition concerns with #232, but it is narrower: the affected custom station already exists, can be placed, and can be assigned. The missing behavior is native interaction feedback on the placed model.