feat: add Typesense backend for search

Support searching forum threads and comments using Typesense as
a backend.

This is completely backwards compatible; Meilisearch can
still be used as the backend with no changes, and existing installations
will continue to be configured to use Meilisearch.

The new backend can be enabled by setting:

```py
TYPESENSE_ENABLED = True
```

You can also manually set the backend for testing with something like:

```py
FORUM_SEARCH_BACKEND = "forum.search.typesense.TypesenseBackend"
```

Configuring the Typesense backend can be done with these settings:

```py
TYPESENSE_API_KEY = "your-secret-api-key"
TYPESENSE_URLS = ["https://typesense-1.example.com:8108", "https://typesense-2.example.com:8108"]
```

The actual implementation differs from the Meilisearch backend
in some areas, mostly for internal efficiency.
For example, a single index is used to cover both threads and comments,
while Meilisearch uses two.
It aims to produce comparable results for searches by end users though.

Private-ref: https://tasks.opencraft.com/browse/BB-9975

Author: samuelallan72

CHANGELOG.rst

@@ -14,7 +14,7 @@ Change Log
 Unreleased
 **********
 
-*
+* Add support for Typesense as the search backend.
 
 0.3.4 – 2025-08-13
 ******************

docs/how-tos/configure_typesense_backend.rst

@@ -0,0 +1,23 @@
+Configuring Typesense Search Backend
+====================================
+
+Forum also supports Typesense as the search backend.
+Typesense as both a single node and as a HA cluster is supported.
+
+This is not the default though; Meilisearch is the default backend.
+
+To configure, you can set the following Django settings for LMS and CMS:
+
+.. code-block:: python
+
+    TYPESENSE_ENABLED = True
+    TYPESENSE_API_KEY = "your-secret-api-key-for-typesense"
+    TYPESENSE_URLS = ["https://typesense-1.example.com:8108", "https://typesense-2.example.com:8108"]
+    # Optional: if you need to manually override the backend path for testing
+    #FORUM_SEARCH_BACKEND = "forum.search.typesense.TypesenseBackend"
+
+Alternately, if you deploy using Tutor, you can use the `tutor-contrib-typesense`_
+plugin, which will automatically deploy a single node Typesense instance
+and configure forum to use it.
+
+.. _tutor-contrib-typesense: https://github.com/open-craft/tutor-contrib-typesense/

docs/how-tos/index.rst

@@ -1,2 +1,8 @@
 How-tos
 #######
+
+.. toctree::
+   :maxdepth: 1
+   :glob:
+
+   ./*