"u_deactivate_trait" gives you the trait for free when attempting to deactivate a trait you don't have.

### Describe the bug

Currently, "u_deactivate_trait" causes the game to give you the trait that gets deactivated, even if you didn't have it originally.

For example, Xedra Evolved's Pooka shapeshifting traits make use of "u_deactivate_trait" in order to deactivate competing traits, for example different tail traits, but currently activating a trait will instead also give your character all competing traits because "u_deactivate_trait" give the player the trait when deactivating it without them having to earn it.
There are likely other places that suffer from this bug.

As far as I know "u_add_trait" already adds traits as needed, so this is probably not necessary.

This currently gives a bunch of extra unearned traits in some situations, and fixing it via json requires workarounds that shouldn't be necessary.

### Attach save file

N/A

### Steps to reproduce

1. Create world with Xedra Evolved + character.
2. Give yourself a trait like "Antlers (Shapeshift)" or "Wolf Tail (Shapeshift)", for example.
3. Activate it.
4. Observe extra added traits.

### Expected behavior

Not giving out unearned traits.

### Screenshots

N/A

### Versions and configuration

- OS: Windows
- OS Version: 10.0.26200.8655 (25H2)
- Game Version: cdda-experimental-2026-06-23-0742-dirty+SDL3 [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],
Xedra Evolved [xedra_evolved] (example)
]

### Additional context

N/A

Start by locating the implementation and callers of u_deactivate_trait, then compare its behavior with u_add_trait. Reproduce the issue using the Xedra Evolved Pooka shapeshifting traits, including competing tail traits. Done means deactivating a trait the character does not have no longer grants that trait, while normal trait activation still works.

Written by the indexing model from the issue text.