chore: import upstream snapshot with attribution

docs/macos/dev/README.md

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+# macOS Development & Distribution
+
+Guides for building and signing the Presenton Electron app on macOS.
+
+| Guide | Description |
+|-------|-------------|
+| [Direct distribution](./direct-distribution.md) | Developer ID signing, notarization, DMG verification, and release commands for distribution outside the Mac App Store |
+| [Mac App Store setup](./mac-app-store-setup.md) | Certificates, provisioning profiles, MAS build commands, and submission notes |
+
+## Quick reference
+
+All commands below run from the `electron/` directory on a Mac.
+
+**First-time setup**
+
+```bash
+cd electron
+npm run setup:env
+```
+
+**Run locally (development)**
+
+```bash
+npm run dev
+```
+
+**Build a DMG (local distribution, not App Store)**
+
+```bash
+npm run build:all
+```
+
+Output is written to `electron/dist/`. The default macOS target is a DMG built via `electron/build.js`.
+
+For public releases outside the Mac App Store, use the signed and notarized direct distribution flow:
+
+```bash
+export APPLE_KEYCHAIN_PROFILE="presenton-notary"
+npm run build:all:mac:signed
+```
+
+That assumes the release Mac already has a **Developer ID Application** certificate and a stored `notarytool` profile named `presenton-notary`. See [Direct distribution](./direct-distribution.md) for the exact one-time setup and verification commands.
+
+**Build for the Mac App Store**
+
+See [Mac App Store setup](./mac-app-store-setup.md) for certificates, provisioning profiles, and signing. Summary:
+
+```bash
+npm run build:all:mas-dev   # development / TestFlight-style testing
+npm run build:all:mas       # distribution / App Store submission
+```
+
+## Related docs
+
+- [Electron dependency strategy](../../electron-dependency-strategy.md) — bundled Chromium, ImageMagick, and export runtime
+- [Project README — Electron section](../../../README.md) — prerequisites and high-level build steps