fix(desktop): ship universal native helpers so capture runs on Intel Macs

[mustafaksaeed]

Summary

The desktop app's native macOS helpers — screen-recorder, cursor-monitor, and window-detector — were committed as arm64-only binaries. On an Intel (x86_64) Mac, every spawn of these helpers failed with EBADARCH (errno -86, "Bad CPU type in executable"), which broke screen recording and screenshot capture entirely:

screenshot capture failed: spawn Unknown system error -86

This rebuilds all three helpers as universal binaries (x86_64 + arm64) so the desktop app runs on both Intel and Apple Silicon. The arm64 slice is preserved, so Apple Silicon behavior is unchanged.

Changes

• apps/desktop/native/screen-recorder/bin/screen-recorder → universal
• apps/desktop/native/cursor-monitor/bin/cursor-monitor → universal
• apps/desktop/native/window-detector/bin/window-detector → universal

Rebuilt from source with the installed Swift toolchain, e.g.:

cd apps/desktop/native/screen-recorder
swiftc -O -target x86_64-apple-macos13.2 RecordingWriter.swift spikes/RecordingTapSpike.swift main.swift -o /tmp/x64
swiftc -O -target arm64-apple-macos13.2  RecordingWriter.swift spikes/RecordingTapSpike.swift main.swift -o /tmp/arm
lipo -create /tmp/x64 /tmp/arm -output bin/screen-recorder

(cursor-monitor and window-detector are single-file swiftc builds.)

Local-dev setup notes (not in this PR — files are gitignored)

Getting a fresh clone running end-to-end on next dev (port 3032) also required local-only config that can't be committed:

• apps/web/.dev.vars — BETTER_AUTH_SECRET (openssl rand -hex 32) and BETTER_AUTH_URL=http://localhost:3032 (fixes Invalid origin / Base URL could not be determined on signup).
• apps/web/.env.local — NEXT_PUBLIC_R2_PUBLIC_BASE_URL=http://localhost:3032/api/r/media so the client loads media through the local proxy instead of the prod CDN (fixes black thumbnails + "bucket may have lost CORS access" in the editor).
• pnpm --filter @captureflow/web db:seed:local to seed local D1.

Note: apps/web/.dev.vars.example documents http://localhost:3000, but next dev actually runs on 3032 (next dev -p 3032) — worth aligning in a follow-up.

Test plan

• On an Intel Mac, launch the desktop app and confirm recording + screenshot capture succeed (no spawn Unknown system error -86).
• On Apple Silicon, confirm capture still works (arm64 slice).
• Verify file apps/desktop/native/*/bin/* reports universal binary with 2 architectures.

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