fix(render): extend high-quality encode timeout

[miguel-heygen]

Summary

• Reserve a 24× source-duration wall-clock budget for high-quality disk-frame encodes.
• Keep the existing 4× budget for draft and standard renders.
• Preserve larger operator-provided FFMPEG_ENCODE_TIMEOUT_MS overrides.

Root cause

PR #2244 made the encode timeout scale to 4× source duration. A 5,177-frame 30 fps Windows high-quality render is 172.56 seconds long, so that policy computes 690,240 ms—the exact reported timeout after all frames had already been captured. High-quality libx264 encoding can exceed 4× realtime on constrained hosts, discarding the completed capture.

Tests

• Exact 172.56-second high-quality regression: red at 690,240 ms; green at 4,141,440 ms.
• Focused encode-stage tests: 8 passed.
• Producer unit suite: 295 tests passed, plus all classified producer lanes.
• Producer typecheck passed.
• Formatting, lint, diff check, and pre-commit checks passed.

Human review is required; this PR is not self-approved or merged.