feat(cli): Add deploy list and deploy delete subcommands (#7106)

### Summary
This PR introduces a subcommand implementation that allows `langgraph
deploy list` and `langgraph deploy delete` subcommands.

#### `langgraph deploy list`
```bash
(env) andrewnguonly@Andrew-Nguonly-KC23X90J02 langgraph % langgraph deploy list --help                                                                              ⎈ gke_langchain-test-387119_us-west1_langgraph-cloud-us-west1
Usage: langgraph deploy list [OPTIONS]

  [Beta] List LangSmith Deployments.

Options:
  --name-contains TEXT  Only show deployments whose names contain this value.
  --api-key TEXT        API key. Can also be set via LANGGRAPH_HOST_API_KEY,
                        LANGSMITH_API_KEY, or LANGCHAIN_API_KEY environment
                        variable or .env file.
  --help                Show this message and exit.
```

Output example:
```bash
(env) andrewnguonly@Andrew-Nguonly-KC23X90J02 cli % langgraph deploy list
Deployment ID                         Deployment Name             Deployment URL                                                                      
------------------------------------  --------------------------  ------------------------------------------------------------------------------------
a40d6567-87c0-485a-a23d-94309a7d4519  ht-andrew-test-04           -                                                                                   
9da26acb-d0c9-4af0-af9e-f3fe8dfe85bc  ht-anirudh-deployment-test  https://ht-anirudh-deployment-test-428af4737f8a533cb2b107587eb8f38f.us.langgraph.app
```

#### `langgraph deploy delete`
```bash
(env) andrewnguonly@Andrew-Nguonly-KC23X90J02 langgraph % langgraph deploy delete --help                                                                            ⎈ gke_langchain-test-387119_us-west1_langgraph-cloud-us-west1
Usage: langgraph deploy delete [OPTIONS] DEPLOYMENT_ID

  [Beta] Delete a LangSmith Deployment.

Options:
  --force         Delete without prompting for confirmation.
  --api-key TEXT  API key. Can also be set via LANGGRAPH_HOST_API_KEY,
                  LANGSMITH_API_KEY, or LANGCHAIN_API_KEY environment variable
                  or .env file.
  --help          Show this message and exit.
```

Output example:
```bash
(env) andrewnguonly@Andrew-Nguonly-KC23X90J02 cli % langgraph deploy delete a40d6567-87c0-485a-a23d-94309a7d4519
Are you sure you want to delete deployment ID a40d6567-87c0-485a-a23d-94309a7d4519? (Y/n): Y
Host API key: 
Deleted deployment a40d6567-87c0-485a-a23d-94309a7d4519.
```

```bash
(env) andrewnguonly@Andrew-Nguonly-KC23X90J02 cli % langgraph deploy delete a40d6567-87c0-485a-a23d-94309a7d4519
Are you sure you want to delete deployment ID a40d6567-87c0-485a-a23d-94309a7d4519? (Y/n): n
Aborted!
```

```bash
(env) andrewnguonly@Andrew-Nguonly-KC23X90J02 cli % langgraph deploy delete 9da26acb-d0c9-4af0-af9e-f3fe8dfe85bc --force
Host API key: 
Deleted deployment 9da26acb-d0c9-4af0-af9e-f3fe8dfe85bc.
```

libs/cli/tests/unit_tests/test_host_backend.py

@@ -135,6 +135,28 @@ def test_list_deployments(client):
     assert result == {"ok": True}
 
 
+def test_list_deployments_sends_query_params():
+    def handler(req: httpx.Request) -> httpx.Response:
+        assert req.url.path == "/v2/deployments"
+        assert req.url.params["name_contains"] == "my app"
+        return httpx.Response(200, json={"ok": True})
+
+    c = HostBackendClient("https://api.example.com", "test-key")
+    c._client = httpx.Client(
+        base_url="https://api.example.com",
+        transport=httpx.MockTransport(handler),
+        headers={"X-Api-Key": "test-key", "Accept": "application/json"},
+        timeout=30,
+    )
+    result = c.list_deployments("my app")
+    assert result == {"ok": True}
+
+
+def test_delete_deployment(client):
+    result = client.delete_deployment("dep-123")
+    assert result == {"ok": True}
+
+
 def test_request_push_token(client):
     result = client.request_push_token("dep-123")
     assert result == {"ok": True}