docs: add page for couchbase_query (CouchbaseQueryVectorStore) and refactor existing Couchbase docs (#1079)

## Overview
- Adds a new page illustrating usage for new CouchbaseQueryVectorStore
(langchain-ai/langchainjs#8333)
- Refactors existing page path to ensure distinction between
couchbase_search and couchbase_query
- Adjusts some language for clarity

## Type of change

**Type:** New documentation page

## Related issues/PRs
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- GitHub issue:
- Feature PR: langchain-ai/langchainjs#8333

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- Linear issue:
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## Checklist
<!-- Put an 'x' in all boxes that apply -->
- [x] I have read the [contributing guidelines](README.md)
- [x] I have tested my changes locally using `docs dev`
- [x] All code examples have been tested and work correctly
- [x] I have used **root relative** paths for internal links
- [x] I have updated navigation in `src/docs.json` if needed
- I have gotten approval from the relevant reviewers

## Additional notes
<!-- Any other information that would be helpful for reviewers -->

---------

Co-authored-by: Lauren Hirata Singh <lauren@langchain.dev>
Co-authored-by: Mason Daugherty <github@mdrxy.com>

Author: 3 people

src/oss/javascript/integrations/providers/all_providers.mdx

@@ -865,10 +865,17 @@ Browse the complete collection of integrations available for JavaScript/TypeScri
   </Card>
 
   <Card
-    title="Couchbase"
-    href="/oss/integrations/vectorstores/couchbase"
+    title="Couchbase Query"
+    href="/oss/integrations/vectorstores/couchbase_query"
+  >
+    Recommended vector search method in Couchbase NoSQL database via query service.
+  </Card>
+
+  <Card
+    title="Couchbase Search"
+    href="/oss/integrations/vectorstores/couchbase_search"
   >
-    NoSQL database with vector search capabilities.
+    Alternative vector search method in Couchbase NoSQL database via search service.
   </Card>
 
   <Card