Panoramic night vision goggles sometimes can't be placed in army helmets

### Describe the bug

Depending on whether the army helmet is small or large, you won't be able to put the goggles in them. I don't know whether it's intended or not, but this is quite janky.

### Attach save file

N/A

### Steps to reproduce

1. Spawn a lot of differently-sized army helmets
2. Try attaching the goggles to each one

### Expected behavior

While I've never used them in real life and can't find information about this, I doubt this is something that would realistically happen or at least the army might provide a variant for smaller helmets.

### Screenshots

_No response_

### Versions and configuration

- OS: Linux
- OS Version: LSB Version: n/a; Distributor ID: EndeavourOS; Description: EndeavourOS Linux; Release: rolling; Codename: rolling;
- Game Version: cdda-experimental-2024-09-20-0455 4254b22 [64-bit]
- Graphics Version: Tiles
- Game Language: System language []
- Mods loaded: [
Dark Days Ahead [dda],
Disable NPC Needs [no_npc_food],
Portal Storms Ignore NPCs [personal_portal_storms],
Slowdown Fungal Growth [no_fungal_growth]
]

### Additional context

If this is not intended, I'll fix it myself.

Start by reproducing the issue with differently-sized army helmets and panoramic night vision goggles, following the listed steps. The payload names no source file or test, so locate the equipment definitions or handling entry point, then verify that the goggles can be attached consistently across helmet sizes.

Written by the indexing model from the issue text.