Add data-space topic

[mjanez]

Please confirm this pull request meets the following requirements:

• I followed the contributing guidelines: https://github.com/github/explore/blob/main/CONTRIBUTING.md.
• This change is not self-promotion.

Which change are you proposing?

• Suggesting edits to an existing topic or collection
• Curating a new topic or collection
• Something that does not neatly fit into the binary options above

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Curating a new topic or collection

• I've formatted my changes as a new folder directory, named for the topic or collection as it appears in the URL on GitHub (e.g. https://github.com/topics/[NAME] or https://github.com/collections/[NAME])
• My folder contains a *.png image (if applicable) and index.md
• All required fields in my index.md conform to the Style Guide and API docs: https://github.com/github/explore/tree/main/docs

Data Spaces are a federated, sovereign data ecosystems. Global Google Trends data from the last 5 years shows a massive spike in developer interest, with searches for "data spaces" up 350% and the "dataspace" alias up 180%. Furthermore, rising queries for specific technical implementations like the "eclipse dataspace connector" and "gaia-x" prove this is no longer just a theoretical concept but an active. The aim of including as topic in GitHub is to help developers find and collaborate on these components and to grow the open-source ecosystem.

[Copilot]

Pull request overview

Adds a new curated Explore topic for “data-space” to help categorize and surface repositories related to sovereign/federated data ecosystems.

Changes:

• Introduces new topic definition with aliases, related topics, short description, and Wikipedia link.
• Adds the topic page body content describing the concept and its key properties.

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[ahpook]

There are only 6 repos with this topic and 30 with dataspace but thanks for the contribution