Support pushing/updating benchmark task kernels via CLI

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Problem

kaggle kernels push fails with Kernel push error: Notebook not found when trying to update a benchmark task kernel (created via the Kaggle Benchmarks UI).

Steps to reproduce

1. Create a benchmark task at https://www.kaggle.com/benchmarks/tasks/new
2. The kernel appears in kaggle kernels list --user <username> and can be pulled with kaggle kernels pull
3. Modify the notebook locally
4. Attempt to push:

$ kaggle kernels pull eugenio0/rule-induction -p /tmp/test -m
# Works fine — pulls notebook + metadata

$ kaggle kernels push -p /tmp/test
Kernel push error: Notebook not found

The metadata file is correct (has the right id, code_file, etc.), and the kernel exists and is accessible via list and pull. But push fails.

Expected behavior

kaggle kernels push should work for benchmark task kernels the same way it works for regular kernels, allowing programmatic updates without manual upload through the UI.

Environment

• Kaggle CLI: 2.0.1
• kagglesdk: 0.1.17
• OS: macOS (Darwin 25.1.0)

Additional context

The kagglesdk package already has benchmarks.services.benchmark_tasks_api_service which suggests the API exists — it's just not exposed through the CLI. This would be valuable for CI/CD workflows where benchmark tasks are version-controlled in git and deployed programmatically.

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Additional findings from investigating the SDK

The kagglesdk (0.1.17) has the API types but the routing is broken:

1. BenchmarkTasksApiClient exists in kagglesdk.benchmarks.services.benchmark_tasks_api_service with a create_benchmark_task() method
2. ApiCreateBenchmarkTaskRequest defines endpoint() returning /api/v1/benchmarks/tasks/push with fields slug (str) and text (str)
3. But KaggleHttpClient._get_request_url() builds gRPC-style URLs: https://api.kaggle.com/v1/benchmarks.BenchmarkTasksApiService/CreateBenchmarkTask → 404
4. Hitting the correct REST endpoint directly (https://api.kaggle.com/api/v1/benchmarks/tasks/push) with Basic auth returns 400 with empty body for all payload formats tried (JSON, form-data, various field names)

So the pieces are all there in the SDK — BenchmarkTasksApiClient, request/response types, endpoint definitions — they're just not wired up correctly in either the HTTP client's URL routing or the CLI's command structure.

Minimal repro with the SDK:

from kagglesdk.benchmarks.services.benchmark_tasks_api_service import BenchmarkTasksApiClient
from kagglesdk.benchmarks.types.benchmark_tasks_api_service import ApiCreateBenchmarkTaskRequest
from kagglesdk.kaggle_http_client import KaggleHttpClient

req = ApiCreateBenchmarkTaskRequest()
req.slug = 'my-task'
req.text = '{"cells": [], "nbformat": 4, "nbformat_minor": 5, "metadata": {}}'

client = BenchmarkTasksApiClient(KaggleHttpClient())
result = client.create_benchmark_task(req)  # → 404