Filtering docker containers by category hides multiple container services

### Description

## Background
- docker container, `glanceapp/glance:v0.8.4`
- configured via container labels

## Steps to reproduce
1. create 2 containers connected to each other via `glance.id`/`glance.parent` and with `glance.category: something` (add name and icon if necessary)
2. create a `docker-containers` widget with `category: something` filter
3. the sub-containers are not shown on icon hover

## Example `docker-compose.yml`
> I stripped out my envs so it might not work simply copy-pasted
```yml
services:
gitea:
image: gitea/gitea:1.21.5
container_name: gitea
depends_on:
- gitea_db
labels:
glance.id: gitea
glance.name: Gitea
glance.icon: sh:gitea
glance.category: external

gitea_db:
image: postgres:14
container_name: gitea-db
restart: unless-stopped
labels:
glance.parent: gitea
glance.name: Postgres
glance.icon: sh:postgres
```

No source file or test is named. Reproduce the issue with the supplied docker-compose.yml pattern, then trace the docker-containers widget's category filtering and parent/child display behavior. Done means a category-filtered parent still reveals its connected sub-containers on icon hover.

Written by the indexing model from the issue text.