v2.0.0-rc.15

Changes since v2.0.0-rc.14

• docs(testing): log the v2.0.0-rc.13 macOS computer-use e2e pass
• docs(testing): restore the macOS RC passes that never reached the results log
• perf(preview): stop decoding the stand-in camera when a clip has none
• docs(preview): record the free-run decode budget and what still falls behind
• test(preview): prove the stand-in never moves, and stop at a source that loops

Full Changelog: v2.0.0-rc.14...v2.0.0-rc.15