Expose taxon admin_url in API and consume in frontend

[coderabbitai]

Problem

Currently, the frontend hardcodes the admin URL for taxa with a production domain and path:

get adminUrl(): string {
  return `https://api.antenna.insectai.org/bereich/main/taxon/${this.id}`
}

This causes two issues:

1. The URL always points to production, even in development and staging environments
2. The path segment varies by environment, and the frontend doesn't have knowledge of these routing rules

Proposed Solution

Move the admin URL logic to the backend, making it the source of truth:

Backend changes (ami/main/api/serializers.py):

• Add an admin_url field (or links.admin) to taxon serializers (TaxonSerializer, TaxonListSerializer, TaxonNoParentNestedSerializer)
• Compute the URL using environment-specific routing rules
• Example:

class TaxonSerializer(serializers.ModelSerializer):
    admin_url = serializers.SerializerMethodField()
    
    def get_admin_url(self, obj):
        request = self.context.get('request')
        return build_admin_url(request, obj.id)

Frontend changes (ui/src/data-services/models/species.ts):

• Consume the admin_url field from the API
• Return undefined if not provided by the backend
• Example:

get adminUrl(): string | undefined {
  return this._species.admin_url ?? this._species?.links?.admin ?? undefined
}

UI behavior:

• Admin button only shows when species.adminUrl is truthy and canUpdate is true
• If backend omits the URL for certain environments or roles, button won't appear

References

• Related PR: Taxon details tweaks #1039
• Discussion: Taxon details tweaks #1039 (comment)
• Requested by: @annavik

[annavik]

Reminder: we should do the same for team permissions URL

[mihow]

Suggestion: construct & return the admins URL from the backend. Return null if the user is does not have the Django is_staff setting set to True.