feat(ambient): add Ambient as a new inference provider

Ambient is an SVM-compatible Layer-1 blockchain providing verified AI
inference via Proof-of-Logits consensus. Its inference API provides
OpenAI-compatible chat completions at https://api.ambient.xyz/v1.

litellm/llms/openai_like/providers.json

@@ -114,5 +114,13 @@
     "param_mappings": {
       "max_completion_tokens": "max_tokens"
     }
+  },
+  "ambient": {
+    "base_url": "https://api.ambient.xyz/v1",
+    "api_key_env": "AMBIENT_API_KEY",
+    "api_base_env": "AMBIENT_API_BASE",
+    "param_mappings": {
+      "max_completion_tokens": "max_tokens"
+    }
   }
 }

provider_endpoints_support.json

@@ -66,6 +66,23 @@
         "a2a": false
       }
     },
+    "ambient": {
+      "display_name": "Ambient (`ambient`)",
+      "url": "https://docs.ambient.xyz/",
+      "endpoints": {
+        "chat_completions": true,
+        "messages": false,
+        "responses": false,
+        "embeddings": false,
+        "image_generations": false,
+        "audio_transcriptions": false,
+        "audio_speech": false,
+        "moderations": false,
+        "batches": false,
+        "rerank": false,
+        "a2a": false
+      }
+    },
     "aiml": {
       "display_name": "AI/ML API (`aiml`)",
       "url": "https://docs.litellm.ai/docs/providers/aiml",