backend/curl handle pause related errors

[bdbai]

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[Copilot]

Pull request overview

This PR improves the curl backend's handling of pause-related errors in the async path. Previously, errors from curl_easy_pause and unpause operations were silently ignored (.ok()). Now they are properly propagated to the consumer as request failures. The write callback is also refactored to use WriteError::Pause (returning CURL_WRITEFUNC_PAUSE) instead of explicitly calling curl_easy_pause from within the callback.

Changes:

• Replace explicit pause_recv() in the write callback with Err(WriteError::Pause) and add error handling for pause_recv() in the header callback
• Propagate errors from unpause_recv()/unpause_send()/pause_send() in the event loop as RequestResult::Done errors instead of silently ignoring them
• Add is_recv_unpause_sent flag to deduplicate unpause requests, and rename poll_bytes_async to wait_for_bytes

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
backends/curl/src/async/handler.rs	Refactored write callback to use WriteError::Pause for backpressure; added error handling for pause_recv() in header callback
backends/curl/src/async/loop.rs	Added is_recv_unpause_sent flag to deduplicate unpause tasks; propagated errors from unpause/pause operations; renamed poll_bytes_async to wait_for_bytes
backends/curl/src/async/pause.rs	Changed pause_recv() to return Result<(), CurlCodeContext> instead of ()
backends/curl/src/state.rs	Added data_available() helper method (async-only)
backends/curl/src/async.rs	Updated call site from poll_bytes_async to wait_for_bytes

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