Add macOS Mac App Store build instructions to README.md

This commit introduces a new section in the README.md detailing the process for building and signing a macOS package for the Mac App Store. It includes requirements for Apple Developer accounts, a manual setup guide for certificates and provisioning profiles, and a command to build the signed upload package. Additionally, it provides instructions for uploading the package to App Store Connect for review.

build_tools/README.md

@@ -77,3 +77,48 @@ This produces:
   --identity "Developer ID Application: Your Name (TEAMID)" \
   --notary-profile "<profile-name>"
 ```
+
+## macOS Mac App Store (MAS) build + signed PKG
+
+This repo includes `build_tools/macos/build_mas_pkg.sh` to automate:
+
+- build (MAS mode) → deploy (bundle deps) → embed provisioning profile → codesign → `productbuild` a signed `.pkg`
+
+### Requirements (Apple Developer)
+
+- An App Store Connect app record with bundle id **`com.dryark.strawberry`** (or your own).
+- A **Mac App Store provisioning profile** for that App ID.
+- Signing identities installed in your Keychain:
+  - **Apple Distribution** (for the `.app`)
+  - **3rd Party Mac Developer Installer** (for the `.pkg`)
+
+Tip: list what you have installed:
+
+```bash
+security find-identity -p codesigning -v
+security find-identity -p basic -v
+ls -la "$HOME/Library/MobileDevice/Provisioning Profiles" | head -n 50
+```
+
+### Manual setup guide (certificates, Keychain Access, profiles)
+
+See: `build_tools/macos/README_MAS.md`
+
+### Build the signed upload PKG
+
+```bash
+./build_tools/macos/build_mas_pkg.sh --run --release --clean \
+  --codesign-identity "Apple Distribution: Your Name (TEAMID)" \
+  --installer-identity "3rd Party Mac Developer Installer: Your Name (TEAMID)" \
+  --provisionprofile "$HOME/Library/MobileDevice/Provisioning Profiles/XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX.provisionprofile"
+```
+
+Output:
+
+- `cmake-build-macos-release-mas/strawberry.app`
+- `cmake-build-macos-release-mas/strawberry-mas.pkg`
+
+### Upload + submit for review
+
+- Upload the `.pkg` using Apple’s **Transporter** app (App Store Connect), or with `iTMSTransporter`.
+- In App Store Connect, wait for processing, select the build, then **Submit for Review**.