Feat: ​​OpenSearch's support for newly embedding models​​ (#10494)

### What problem does this PR solve?

fix issues：https://github.com/infiniflow/ragflow/issues/10402

As the newly distributed embedding models support vector dimensions max
to 4096, while current OpenSearch's max dimension support is 1536.
As I tested, the 4096-dimensions vector will be treated as a float type
which is unacceptable in OpenSearch.

Besides, OpenSearch supports max to 16000 dimensions by defalut with the
vector engine(Faiss). According to:
https://docs.opensearch.org/2.19/field-types/supported-field-types/knn-methods-engines/

I added max to 10240 dimensions support for OpenSearch, as I think will
be sufficient in the future.

As I tested , it worked well on my own server (treated as knn_vector)by
using qwen3-embedding:8b as the embedding model:
<img width="1338" height="790" alt="image"
src="https://github.com/user-attachments/assets/a9b2d284-fcf6-4cea-859a-6aadccf36ace"
/>


### Type of change

- [x] New Feature (non-breaking change which adds functionality)


By the way, I will still focus on the stuff about
Elasticsearch/Opensearch as search engines and vector databases.

Co-authored-by: 张雨豪 <zhangyh80@chinatelecom.cn>

conf/os_mapping.json

@@ -200,6 +200,61 @@
           }
         }
       },
+      {
+        "knn_vector": {
+          "match": "*_2048_vec",
+          "mapping": {
+            "type": "knn_vector",
+            "index": true,
+            "space_type": "cosinesimil",
+            "dimension": 2048
+          }
+        }
+      },
+      {
+        "knn_vector": {
+          "match": "*_4096_vec",
+          "mapping": {
+            "type": "knn_vector",
+            "index": true,
+            "space_type": "cosinesimil",
+            "dimension": 4096
+          }
+        }
+      },
+      {
+        "knn_vector": {
+          "match": "*_6144_vec",
+          "mapping": {
+            "type": "knn_vector",
+            "index": true,
+            "space_type": "cosinesimil",
+            "dimension": 6144
+          }
+        }
+      },
+      {
+        "knn_vector": {
+          "match": "*_8192_vec",
+          "mapping": {
+            "type": "knn_vector",
+            "index": true,
+            "space_type": "cosinesimil",
+            "dimension": 8192
+          }
+        }
+      },
+      {
+        "knn_vector": {
+          "match": "*_10240_vec",
+          "mapping": {
+            "type": "knn_vector",
+            "index": true,
+            "space_type": "cosinesimil",
+            "dimension": 10240
+          }
+        }
+      },
       {
         "binary": {
           "match": "*_bin",