Go: implement Rerank in Replicate driver (#15278)

### What problem does this PR solve?

`ReplicateModel.Rerank` in `internal/entity/models/replicate.go` was a
`"replicate, no such method"` stub. The chat path landed in #14958 and
the embed path in #15073; rerank is the last major retrieval surface
still missing on this provider.

Until this PR, a tenant who selected a Replicate reranker model got the
sentinel error on every rerank call.

Co-authored-by: sxxtony <sxxtony@users.noreply.github.com>
Co-authored-by: Jin Hai <haijin.chn@gmail.com>

conf/models/replicate.json

@@ -29,6 +29,13 @@
       "model_types": [
         "embedding"
       ]
+    },
+    {
+      "name": "yxzwayne/bge-reranker-v2-m3:7f7c6e9d18336e2cbf07d88e9362d881d2fe4d6a9854ec1260f115cabc106a8c",
+      "max_tokens": 8192,
+      "model_types": [
+        "rerank"
+      ]
     }
   ]
 }