Usage statistics not recorded when upstream returns 0 tokens

[LucasInsight]

Describe the bug

When an upstream model API returns a successful response but explicitly sets all token usage metrics to 0 (e.g., "total_tokens": 0), the request is entirely excluded from CLIProxyAPI's usage statistics aggregation.

While it is correct to filter out empty chunks from streams to prevent spam, a completed request that happens to report 0 tokens should still be recorded as a valid request/transaction in the usage statistics (so the request count increments), rather than being silently dropped.

Steps to reproduce

1. Configure a provider that returns "usage": {"prompt_tokens": 0, "completion_tokens": 0, "total_tokens": 0} in its successful JSON response.
2. Enable usage-statistics-enabled: true in the config.
3. Make a chat completion request to this model.
4. Observe that the token/request usage in the management dashboard remains unchanged for this key/model.

Expected behavior

The request should be recorded in the in-memory usage statistics (incrementing the request count) even if the token delta is 0.

Related PR

A fix for this has been submitted in PR #2272, which adds the missing ensurePublished safety calls to the affected executors.