perf(benchmark): record the classic desktop baseline

[doodlewind]

Summary

• add a reproducible macOS release benchmark harness for the classic System
• record logical artifact sizes, ten spawn-to-first-frame samples, settled RSS, physical footprint, and process count
• preserve raw samples, exact Pocket Desktop/PocketJS commits, machine identity, and protocol caveats

Result

• 25.35 MiB complete installed runtime
• 179.62 ms process-cold/cache-warm median to first painted frame
• 86.73 MiB settled RSS and 294.24 MiB macOS physical footprint
• one native process for the System UI plus 11 installed AppInstances

Validation

• bun run build
• bun run benchmark:classic --quick
• bun run benchmark:classic
• bun run check
• git diff --check