[ sky island ] kill 5 non-zombie birds mission not completing

### Describe the bug

went on an expedition, got a task to kill any 5 non-zombie birds.

killed four canadian geese, then killed five ravens, quest did not complete.

possibly related to the fact i killed them by running them over, but if that's the problem, it should still work, the game generally credits the player with other vehicular omnicide events

### Attach save file

[Henlopen Acres-trimmed.tar.gz](https://github.com/user-attachments/files/26415670/Henlopen.Acres-trimmed.tar.gz)

### Steps to reproduce

get mission, kill birds, fail to profit?

attached save has the mission still active, and the history is set to 10k lines, so you can see the bird deaths logged there

### Expected behavior

warp shard payout, yo

### Screenshots

### Versions and configuration

- OS: Linux
- OS Version: Distributor ID: Ubuntu; Description: Ubuntu 24.04.4 LTS; Release: 24.04; Codename: noble;
- Game Version: cdda-experimental-2026-04-01-0512 ef53e38-dirty [64-bit]
- Graphics Version: Tiles
- Game Language: English [en]
- Mods loaded: [
Dark Days Ahead [dda],
Disable NPC Needs [no_npc_food],
Portal Storms Ignore NPCs [personal_portal_storms],
Bombastic Perks [bombastic_perks],
Sky Island [skyisland]
]

### Additional context

_No response_

Load Henlopen.Acres-trimmed.tar.gz and inspect the active Sky Island mission and its history, which records the bird deaths. Reproduce the objective by killing the listed non-zombie birds, including by vehicle, then trace the mission's kill-credit handling. Done means the five qualifying kills complete the mission and award the warp shard payout.

Written by the indexing model from the issue text.