feat(v2): add OllamaCloud() constructor for Ollama Cloud

Ollama Cloud (https://ollama.com) requires a Bearer-token API key and
exposes the same /api/chat surface as local Ollama. OllamaCloud(apiKey)
returns a client preconfigured for the cloud endpoint; Ollama() remains
the local-instance constructor.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

v2/constructors.go

@@ -104,8 +104,9 @@ func Groq(apiKey string, opts ...ClientOption) *Client {
 	return NewClient(groqProvider.New(apiKey, cfg.baseURL))
 }
 
-// Ollama creates a client for a local Ollama instance (OpenAI-compatible).
-// No API key is required. Use WithBaseURL to point at a non-default host/port.
+// Ollama creates a client for a local Ollama instance using the native
+// /api/chat endpoint. No API key is required. Use WithBaseURL to point at a
+// non-default host/port.
 //
 // Example:
 //
@@ -117,3 +118,22 @@ func Ollama(opts ...ClientOption) *Client {
 	}
 	return NewClient(ollamaProvider.New("", cfg.baseURL))
 }
+
+// OllamaCloud creates a client targeting Ollama Cloud (https://ollama.com).
+// The apiKey is required and is sent as `Authorization: Bearer <key>`. Use
+// WithBaseURL to point at a private Ollama deployment that requires auth.
+//
+// Example:
+//
+//	model := llm.OllamaCloud(os.Getenv("OLLAMA_API_KEY")).Model("kimi-k2.5")
+func OllamaCloud(apiKey string, opts ...ClientOption) *Client {
+	cfg := &clientConfig{}
+	for _, opt := range opts {
+		opt(cfg)
+	}
+	baseURL := cfg.baseURL
+	if baseURL == "" {
+		baseURL = ollamaProvider.DefaultCloudBaseURL
+	}
+	return NewClient(ollamaProvider.New(apiKey, baseURL))
+}