Allow content to be submitted to the assets section directly from the website

### Observation

Currently, adding content to the assets section requires opening a GitHub pull request.

This makes sense for developers who maintain libraries, plugins, or technical assets. These contributors are usually familiar with GitHub and open-source workflows.

However, this process may be too much friction for game developers who simply want to submit a game made with Bevy.

Many game developers are not necessarily open-source contributors. They may not be comfortable creating a pull request just to add their game to the website.

Because of this, I suspect many games made with Bevy are missing from the website, not because they are not worth showing, but because the submission process is too technical or inconvenient.

#### Related discussions

Bevy Asset Store - showcases! #1277

### Suggestion

It could be useful to allow some types of content — especially games made with Bevy — to be submitted directly from the website.

For example, a submission form could allow users to provide:
- project name;
- short description;
- screenshots;
- video or GIF;
- itch.io / Steam / website link;
- source code link, if available;
- Bevy version, if relevant;
- tags such as 2D, 3D, puzzle, roguelike, multiplayer, etc.

Submissions could still require moderation before publication.

### Example from another engine

[Godot has an asset library](https://godotengine.org/asset-library/asset) that can be browsed and interacted with directly from the website.

The goal would not necessarily be to reproduce the exact same system, but the idea of lowering the contribution barrier is interesting.

### Expected impact

Making submissions easier could lead to more games being showcased on the Bevy website.

This would help newcomers better understand what can already be built with Bevy and could create a stronger “wow” effect when discovering the engine.

A richer showcase of real projects could also increase confidence in the ecosystem.

### Possible implementation direction

One possible approach would be to create a small API using a web framework, with a JavaScript frontend to interact with it. This is [the way chosen by Godot](https://github.com/godotengine/godot-asset-library).

Start by reviewing the existing Bevy website asset-submission flow, then compare the proposed experience with the linked Godot asset library example. Define the submission form, moderation process, supported fields, and publication flow before implementation; done means users can submit game content directly from the website and moderators can approve it.

Written by the indexing model from the issue text.