feat: add AI Bridge request logs model filter (#22230)

This pull-request implements a simple filtering logic so that we're able
to pick which model the user actually used when logs were sent to AI
Bridge.

- Add `GET /aibridge/models` API endpoint that returns distinct model
names from AI Bridge interceptions, with pagination and search support
- New `ListAIBridgeModels` SQL query using case-sensitive prefix
matching (`LIKE model || '%'`) to allow B-tree index usage
- Hand-written `ListAuthorizedAIBridgeModels` in `modelqueries.go` for
RBAC authorization filter injection
- `AIBridgeModels` search query parser in searchquery/search.go
(defaults bare terms to the `model` field)
- dbauthz wrappers, dbmetrics, and dbmock implementations for the new
query

<img width="292" height="185" alt="image"
src="https://github.com/user-attachments/assets/134771df-2d26-4c54-acc4-27f58128b351"
/>

docs/reference/api/aibridge.md

@@ -104,3 +104,36 @@ curl -X GET http://coder-server:8080/api/v2/aibridge/interceptions \
 | 200    | [OK](https://tools.ietf.org/html/rfc7231#section-6.3.1) | OK          | [codersdk.AIBridgeListInterceptionsResponse](schemas.md#codersdkaibridgelistinterceptionsresponse) |
 
 To perform this operation, you must be authenticated. [Learn more](authentication.md).
+
+## List AI Bridge models
+
+### Code samples
+
+```shell
+# Example request using curl
+curl -X GET http://coder-server:8080/api/v2/aibridge/models \
+  -H 'Accept: application/json' \
+  -H 'Coder-Session-Token: API_KEY'
+```
+
+`GET /aibridge/models`
+
+### Example responses
+
+> 200 Response
+
+```json
+[
+  "string"
+]
+```
+
+### Responses
+
+| Status | Meaning                                                 | Description | Schema          |
+|--------|---------------------------------------------------------|-------------|-----------------|
+| 200    | [OK](https://tools.ietf.org/html/rfc7231#section-6.3.1) | OK          | array of string |
+
+<h3 id="list-ai-bridge-models-responseschema">Response Schema</h3>
+
+To perform this operation, you must be authenticated. [Learn more](authentication.md).