fix(producer): a BeginFrame capture failure re-renders on a screenshot session - #7070

What

When a render's streaming capture fails in BeginFrame mode, the render restarts once on a fresh screenshot session, whatever the failure was. Before, only stalls, encoder death, transient browser errors and drawElement failures restarted; any other BeginFrame capture failure failed the render.

Why

On Linux with chrome-headless-shell, BeginFrame capture is noticeably faster than screenshot capture, and hosts that opt into it (PRODUCER_FORCE_SCREENSHOT=false) want that speed without a new way to fail. Screenshot capture is the baseline every other fallback already returns to, so a BeginFrame-only failure should cost one re-render, not the render.

Related work

Refs #7066 (a render request can force screenshot capture). Together they let a caller retry in screenshot mode, and make the engine do the same inside one attempt.

How

• shouldRetryViaPinnedFallback takes isBeginFrameCapture: true means the failed attempt captured through BeginFrame, and that alone allows the restart. Cancellation and encoder interruption still never restart.
• The streaming catch sets it from the failed attempt's plan: not forced to screenshot, not drawElement, and resolveParallelCaptureMode resolved beginframe for this render.
• The restart goes through the existing replanAfterFailure, which always sets forceScreenshot: true, so the restarted attempt is not BeginFrame and a second failure is final.

Scope: the streaming route. Distributed chunks already have their own whole-chunk screenshot retry (runCaptureWithScreenshotFallback).

Test plan

• Unit tests added/updated: renderOrchestrator.beginFrameRetry.test.ts runs executeRenderJob with the streaming stage scripted per attempt.
  • A non-stall capture failure in a BeginFrame attempt restarts with forceScreenshot: true. Fails without the fix: the render rejects with the capture error after one attempt.
  • An attempt that already captured in screenshot mode does not restart.
  • A second failure after the screenshot restart is final.
• Mutations: dropping the isBeginFrameCapture branch, or passing false at the call site, each fail the two restart tests.
• renderOrchestrator.test.ts (295), renderOrchestrator.stall.test.ts (9), renderOrchestrator.segmentedDeRetry.test.ts (7) pass; new file passes three runs in a row; tsc --noEmit, oxlint, oxfmt, comment ratchet clean.
• Manual testing performed: in a Linux container with PRODUCER_FORCE_SCREENSHOT=false, a composition that froze the page tripped the BeginFrame watchdog and the engine restarted it on a screenshot session within the same render.
• Documentation updated (if applicable)
• Comments follow CONTRIBUTING.md "Comments"