fix(docs): apply api-nr selectors to nargo-doc pages

The follow-up to #23042: that PR fixed the indexing rate-limit problem
but every aztec-nr-api page still emitted 0 records. Root cause: the
docsearch-scraper resolves a URL's selectors_key by walking start_urls
in order and matching with `re.search` (substring), breaking on first
match. With the homepage URL listed first, every aztec-nr-api URL
matched it (since "https://docs.aztec.network/" is a substring of every
aztec-nr-api URL) and was assigned the default selectors. The default
selectors target Docusaurus-only markup (`header h1`, `article p`,
`menu__list ... active` XPath), none of which exist on rustdoc-style
nargo-doc pages, so the scraper found no nodes and emitted no records.

Fix: list the more-specific aztec-nr-api start_url first so it wins
the selectors_key match for those URLs. The homepage start_url then
serves as the catch-all for everything else.

Reference: scraper/src/strategies/abstract_strategy.py
get_selectors_set_key() iterates start_urls in declaration order and
breaks on the first re.search hit.

Author: critesjosh

docs/typesense.config.json

@@ -1,14 +1,14 @@
 {
   "index_name": "aztec-docs",
   "start_urls": [
-    {
-      "url": "https://docs.aztec.network/",
-      "page_rank": 10
-    },
     {
       "url": "https://docs.aztec.network/aztec-nr-api/mainnet/",
       "selectors_key": "api-nr",
       "page_rank": 2
+    },
+    {
+      "url": "https://docs.aztec.network/",
+      "page_rank": 10
     }
   ],
   "stop_urls": [