Fix Genesis City featured place rankings being overwritten daily

## Description

Genesis City scenes set as featured (highlighted) with a manual ranking are being silently overwritten each day, causing them to fall to the bottom of the Featured Places list. Scenes in Worlds are **not** affected — only Genesis City scenes.

The affected scenes (KoA / Knights of Antrom and Old McTigers) are manually ranked at positions 2 and 3, but each day they reset to positions 21 and 22.

This started around Wednesday 2026-08-20 and reproduces at 100%.

## Steps to Reproduce

1. Manually set a featured Genesis City scene's ranking via the admin API (e.g. KoA at position 2).
2. Wait until the following day.
3. Check the Featured Places list — the scene will have moved to the bottom.

## Expected Behavior

Manually assigned rankings for Genesis City featured scenes persist and are not overwritten by any background sync or external process.

## Actual Behavior

Genesis City scene rankings reset daily. Worlds scene rankings are unaffected. The admin ranking must be manually re-applied each day to restore the correct order.

## Context

- Known risk area: highlighted Genesis City rankings can be overwritten by external/admin/stale sync because the API has no ranking lock.
- Worlds highlighted places use a separate `/api/worlds` endpoint and appear unaffected.
- The regression started around 2026-08-20.

## Affected Scenes

| Scene | Expected position | Actual position after reset |
|-------|------------------|-----------------------------|
| Knights of Antrom (KoA) | 2 | 21 |
| Old McTigers | 3 | 22 |

---

Reported by Bay Backner

Requested by Dawid Krajewski (<@U079GRD9WTZ>)