`ocr review --timeout` does not extend the five-minute LLM request deadline

## Environment

- `open-code-review v1.11.3` (`b3badd376`), darwin/arm64
- JSON agent-mode range review
- One selected Rust file, `zai-anthropic` provider, `glm-5.3`, concurrency 1

## Reproduction

Run a single-file review with an outer timeout larger than five minutes:

```sh
ocr review \
--audience agent \
--format json \
--provider zai-anthropic \
--model glm-5.3 \
--concurrency 1 \
--timeout 30 \
--from BASE \
--to HEAD \
--exclude 'all,other,changed,files'
```

The selected file was 291 lines. Planning completed on the first run, but the main request failed after exactly five minutes. The manifest reported:

```json
{
"classification": "timeout",
"reason": "file review exceeded its time limit",
"duration_to_headers_ms": 300002
}
```

Resuming the session with the same `--timeout 30` started planning again rather than reusing the completed plan. That planning request also failed at exactly five minutes before OCR moved to the main request.

Grouped reviews showed the same `duration_to_headers_ms` of about 300,000 ms despite `--timeout 600`.

## Expected behavior

`--timeout`, documented in minutes as the concurrent task timeout, should either:

1. apply to the provider request deadline needed to complete that task, or
2. document the independent five-minute provider-request ceiling and retry requests that time out before the task deadline.

A resume should reuse a completed plan when the file's main review was the failed stage.

## Impact

A review can repeatedly fail to cover one changed file even when the caller grants a larger task timeout. The JSON correctly marks coverage as failed, but there is no CLI setting that allows the file review to finish.

Start by tracing the `ocr review` command's `--timeout` handling through provider requests, planning, and the resume path; compare the task timeout with the observed five-minute deadline in the manifest. Reproduce the single-file and grouped-review cases, then verify that a larger timeout is honored or its independent ceiling is documented and that a failed main review reuses a completed plan.

Written by the indexing model from the issue text.