If too many smartgunners/specs get set to foxtrot the slot bugs out.

## Testmerges
#10999: 'Fix of various plane related issues' by Blundir at commit f85a7153c4
#10908: 'Adds additional checks to pouncing up a z level' by Git-Nivrak at commit 040e0c0f87
#10925: 'Cape River Mining Colony - Ground Map' by Steelpoint at commit 9e2e0a49ba
#11326: 'Fixes facehuggers ignoring hug proof equipment.' by realforest2001 at commit 85a2ce4287
#11290: 'Ice v2 multizboogaloo DO NOT MERGE' by cuberound at commit 627d08965e
#11170: '[WIP] Yautja Survivor' by realforest2001 at commit 2650086da9
#10623: 'A.S.S - Assault, Support, Security' by Git-Nivrak at commit 91fca19d42
#11389: 'Yautja Leap' by realforest2001 at commit d87e1898b1

## Round ID
31628

## Description of the bug
Sometimes these and other roles get randomly set to foxtrot due to blackcrystallic PR's. When this happens, even though the role is selectable to late join, upon trying to join chat prints "Smartgunner is not available with your current squad preferences."

## What's the difference with what should have happened?
marines should not be getting set to foxtrot unless they are part of the foxtrot tech buy.

## How do we reproduce this bug?
1. get two smartgunners set to foxtrot
2. you can't join as smartgunner even though the slot is opened.

## Attached logs
```
N/A
```

## Additional details
- Author: SmellyHippie
- Admin: SmellyHippie
- Note: None

No file or test is named. Reproduce the two-smartgunner scenario from the issue, then trace the role and squad-preference handling that reports “Smartgunner is not available with your current squad preferences.” Done means regular marines remain selectable as smartgunner unless they are part of the Foxtrot tech buy.

Written by the indexing model from the issue text.