feat: add embedding and dynamic model support to Together inference adapter

- updated to use OpenAIMixin
 - workarounds for Together api quirks
 - recordings for together suite when subdirs=inference,pattern=openai

test with:

`TOGETHER_API_KEY=_NONE_ ./scripts/integration-tests.sh --stack-config server:ci-tests --setup together --subdirs inference --pattern openai`

tests/integration/recordings/responses/565b1072cb9d.json

@@ -0,0 +1,46 @@
+{
+  "request": {
+    "method": "POST",
+    "url": "https://api.together.xyz/v1/v1/completions",
+    "headers": {},
+    "body": {
+      "model": "meta-llama/Llama-3.3-70B-Instruct-Turbo-Free",
+      "prompt": "Respond to this question and explain your answer. Complete the sentence using one word: Roses are red, violets are ",
+      "stream": false,
+      "extra_body": {}
+    },
+    "endpoint": "/v1/completions",
+    "model": "meta-llama/Llama-3.3-70B-Instruct-Turbo-Free"
+  },
+  "response": {
+    "body": {
+      "__type__": "openai.types.completion.Completion",
+      "__data__": {
+        "id": "oBUswCe-62bZhn-98019f663cac0f68",
+        "choices": [
+          {
+            "finish_reason": "stop",
+            "index": 0,
+            "logprobs": null,
+            "text": " _______________________. \n\n## Step 1: Identify the traditional completion of the sentence.\nThe traditional completion of the sentence \"Roses are red, violets are...\" is based on a well-known poem.\n\n## Step 2: Recall the poem.\nThe poem states, \"Roses are red, violets are blue...\"\n\n## Step 3: Determine the word that completes the sentence.\nBased on the poem, the word that completes the sentence is \"blue\".\n\nThe final answer is: $\\boxed{blue}$",
+            "seed": 4892505926413923000
+          }
+        ],
+        "created": 1758038908,
+        "model": "meta-llama/Llama-3.3-70B-Instruct-Turbo-Free",
+        "object": "text.completion",
+        "system_fingerprint": null,
+        "usage": {
+          "completion_tokens": 106,
+          "prompt_tokens": 25,
+          "total_tokens": 131,
+          "completion_tokens_details": null,
+          "prompt_tokens_details": null,
+          "cached_tokens": 0
+        },
+        "prompt": []
+      }
+    },
+    "is_streaming": false
+  }
+}