Add mangal.io ecological networks database to kg-registry (Issue #482)

[caufieldjh]

Description

This PR addresses issue #482 by adding mangal.io to the kg-registry.

Resource Details

mangal.io is a collaborative platform and database for ecological network data, providing:

Key Features

• Network Database: Collection of published food webs, pollination networks, plant-herbivore networks, and other species interaction networks from scientific literature
• Web Portal: Interactive interface for browsing, querying, and visualizing ecological networks
• RESTful API: Programmatic access to network data and metadata (https://api.mangal.io/)
• Visualization Tools: Built-in tools for exploring network structures and properties
• Analysis Platform: Tools for analyzing network metrics and properties

Data Coverage

• Food webs and trophic networks
• Pollination networks
• Plant-herbivore interaction networks
• Parasite-host networks
• Mutualistic networks
• Other biotic interaction networks

Metadata

• Category: DataSource
• Domains: Ecology, Biodiversity, Environmental Science
• License: CC BY 4.0
• Taxon Coverage: Metazoa (Animals), Green Plants
• Collection: BER (Biodiversity/Ecology/Environmental Resources)

Implementation

• Created new resource entry at resource/mangal/mangal.md
• Includes portal access, API endpoint, and documentation
• Added appropriate taxon annotations for discoverability

Testing

The resource entry follows the standard kg-registry format and will be:

• Indexed in the main registry on build
• Discoverable via taxon filtering (Metazoa, Green Plants)
• Accessible through the web interface with full metadata

Related Issue

Closes #482