[Feature Request]: Improve messaging when all channel videos are filtered out

### Guidelines

- [x] I have [searched the issue tracker for open and closed issues](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aissue+sort%3Arelevance-desc) that are similar to the feature request I want to file, without success.
- [x] I have searched the [documentation](https://docs.freetubeapp.io/) for information that matches the description of the feature request I want to file, without success.
- [x] This issue contains only one feature request.
- [x] I have read and agree to follow the [rules](https://docs.freetubeapp.io/community/rules/).

### Problem Description

1. Go to https://www.youtube.com/channel/UC2EiGVmCeD79l_vZ204DUSw/videos
2. See empty page with message `This channel does not currently have any videos`
3. Click on `Fetch more results`
4. See more content being loaded

### Proposed Solution

The `This channel does not currently have any videos` should be changed when there is a `Fetch more results` button available

### Alternatives Considered

None

### Issue Labels

display more information to user

### FreeTube Version

v0.25.2-nightly-7648 Beta

### Operating System Version

Windows 11 IoT Enterprise LTSC 24H2

### Installation Method

.exe

### Upload screenshots or videos

_No response_

### Additional Information

_No response_

Reproduce the channel page using the URL and steps in the issue, then trace the channel video view around the empty-state message and the Fetch more results control. Done means the message communicates that more results can be fetched when that button is available, while the existing no-videos message remains appropriate otherwise.

Written by the indexing model from the issue text.