Dark theme ?

### Steps to reproduce

1.
2.
3.
4.

### Expected behavior

### Actual behavior

Screenshot:

### Your environment

| Description | Value |
| -------------- | ------------ |
| Adguard Content Blocker version:| (e.g. 1.6.10)|
| Browser in use:| (Samsung Interner/Yandex Browser)|
| Filters enabled in Adguard:| (e.g. English, Annoyances)|
| Device model:| (e.g. Google Pixel)|
| Operating system and version:| (e.g. Android 7.1.2)|
| Rooted or not? | (Yes/No) |

The report only requests a dark theme and contains no implementation location, reproduction steps, environment details, or acceptance criteria. Start by locating the Android UI theme resources and existing theme configuration, then clarify which screens, browsers, and visual behavior are in scope before deciding what completion means.

索引モデルが issue の本文から書いたものです。