fix(aimlapi): send attribution headers on every aimlapi.com request (#17491)

### Summary

The **aimlapi.com** provider added in #17311 does not identify itself on
any of its outgoing requests, so its traffic cannot be attributed to the
integration. This PR adds the two headers AIMLAPI expects —
`X-AIMLAPI-Source` and `X-AIMLAPI-Partner-ID` — to every request the
provider makes.

rag/llm/embedding_model.py

@@ -29,6 +29,7 @@ from openai import OpenAI
 from zai import ZhipuAiClient
 
 from common import settings
+from common.aimlapi_utils import attribution_headers
 from common.exceptions import ModelException
 from common.token_utils import num_tokens_from_string, truncate, total_token_count_from_response
 from rag.llm.key_utils import _normalize_replicate_key
@@ -362,6 +363,7 @@ class AIMLAPIEmbed(OpenAIEmbed):
     def __init__(self, key, model_name="text-embedding-3-small", base_url=""):
         base_url = base_url or os.environ.get("AIMLAPI_API_URL", "https://api.aimlapi.com/v1")
         super().__init__(key, model_name, base_url)
+        self.client = self.client.with_options(default_headers=attribution_headers())
         logging.info("[aimlapi.com] Embedding initialized with model %s", model_name)