refactor(search): use typed OpenSearch SDK request body

Pull in @opensearch-project/opensearch only for its
Search_RequestBody type so the inline search body is
type-checked. Also drops the unsupported
highlight.content.boundary_scanner_locale option.

src/search/opensearch.ts

@@ -1,3 +1,4 @@
+import type { API } from "@opensearch-project/opensearch";
 import { log } from "../log.ts";
 
 const OPENSEARCH_URL = Deno.env.get("OPENSEARCH_URL");
@@ -185,7 +186,9 @@ export const searchNotes = async (
     filters.push({ term: { did: opts.did } });
   }
 
-  const body: Record<string, unknown> = {
+  const searchAfter = opts.cursor ? decodeCursor(opts.cursor) : undefined;
+
+  const body: API.Search_RequestBody = {
     size: limit,
     query: {
       bool: {
@@ -207,20 +210,15 @@ export const searchNotes = async (
           fragment_size: 200,
           number_of_fragments: 1,
           boundary_scanner: "sentence",
-          boundary_scanner_locale: "en-US",
         },
         title: { number_of_fragments: 0 },
       },
     },
     sort: [{ _score: "desc" }, { rkey: "desc" }],
     _source: ["did", "rkey", "title", "content", "publishedAt"],
+    ...(searchAfter ? { search_after: searchAfter } : {}),
   };
 
-  if (opts.cursor) {
-    const decoded = decodeCursor(opts.cursor);
-    if (decoded) body.search_after = decoded;
-  }
-
   const res = await request("POST", `/${OPENSEARCH_INDEX}/_search`, body);
   if (!res.ok) {
     const text = await res.text();