Right-click inventory item should open UFOpaedia entry

[ayrtondenner]

Description

Port of upstream OpenApoc#1571.

In the original X-COM: Apocalypse, right-clicking an item in the agent or vehicle equip screen opens its corresponding UFOpaedia entry. Currently in OpenApoc, right-click behaves the same as left-click (drag & drop).

Scope

Modify two files:

• game/ui/general/aequipscreen.cpp — Agent equip screen
• game/ui/base/vequipscreen.cpp — Vehicle equip screen

Add right-click detection, UFOpaedia entry lookup (via UfopaediaEntry::data_id), and open UfopaediaCategoryView.

Testing Checklist

• Agent equip — paper doll: Right-click item on paper doll → opens UFOpaedia entry
• Agent equip — inventory bar: Right-click item in bottom inventory → opens UFOpaedia entry
• Agent equip — left-click unchanged: Left-click still drags items as before
• Vehicle equip — mounted items: Right-click equipped vehicle item → opens UFOpaedia entry
• Vehicle equip — inventory items: Right-click item in vehicle inventory → opens UFOpaedia entry
• Vehicle equip — left-click unchanged: Left-click still drags items as before
• Empty slot: Right-click on empty slot → no crash, nothing happens
• No UFOpaedia entry: Right-click item without UFOpaedia entry → nothing happens gracefully
• While dragging: Right-click while dragging an item → no interference with drag state
• Enemy mode: Right-click does nothing in Enemy mode on agent equip screen