/opensearch.xml names the JSON search too, so an agent that reads the descriptor finds GET /api/v1/search

The forge's search descriptor serves people and agents alike. Today production's /opensearch.xml has only the text/html template and rel=self.

Done:

[ ] src/web/opensearch.ts adds <Url type="application/json" method="get" template="<origin>/api/v1/search?q={searchTerms}"/>, with the origin escaped as the other templates are.
[ ] test/opensearch.test.ts asserts it, and that GET on the filled template answers 200 application/json.

Files: src/web/opensearch.ts, test/opensearch.test.ts. Risk: none.

/opensearch.xml names the JSON search too, so an agent that reads the descriptor finds GET /api/v1/search #8356