feat: add close() method and context manager support to Client and AsyncClient

- Add close() method to Client and AsyncClient for explicit resource cleanup
- Implement __enter__/__exit__ for Client to support context manager usage
- Implement __aenter__/__aexit__ for AsyncClient to support async context manager usage
- Allows usage: with Client() as client: ...
- Allows usage: async with AsyncClient() as client: ...

Closes #532

ollama/_client.py

@@ -124,6 +124,19 @@ class Client(BaseClient):
   def __init__(self, host: Optional[str] = None, **kwargs) -> None:
     super().__init__(httpx.Client, host, **kwargs)
 
+  def close(self) -> None:
+    """Close the underlying HTTP client and release resources."""
+    self._client.close()
+
+  def __enter__(self):
+    """Support usage as a context manager."""
+    return self
+
+  def __exit__(self, exc_type, exc_val, exc_tb):
+    """Ensure the client is closed when exiting the context."""
+    self.close()
+    return False
+
   def _request_raw(self, *args, **kwargs):
     try:
       r = self._client.request(*args, **kwargs)
@@ -686,6 +699,19 @@ class AsyncClient(BaseClient):
   def __init__(self, host: Optional[str] = None, **kwargs) -> None:
     super().__init__(httpx.AsyncClient, host, **kwargs)
 
+  async def close(self) -> None:
+    """Close the underlying HTTP client and release resources."""
+    await self._client.aclose()
+
+  async def __aenter__(self):
+    """Support usage as an async context manager."""
+    return self
+
+  async def __aexit__(self, exc_type, exc_val, exc_tb):
+    """Ensure the client is closed when exiting the async context."""
+    await self.close()
+    return False
+
   async def _request_raw(self, *args, **kwargs):
     try:
       r = await self._client.request(*args, **kwargs)