feat(macos): Developer ID signed .pkg build for Print Stamp

Adds platform/macos/pkg/build-pkg.sh: universal verae-print, Verae Print
Stamp.app, IPP LaunchAgent postinstall, productbuild + notarytool staple.
Uses FlightLookup signing.env (same as Verae Timestamping.app).

README.md

@@ -56,9 +56,32 @@ Channels:
 - `verae` (default) — `api.veraetime.net` + JWT in `~/.verae/auth.properties`
 - `zapier` — `zap.verae.ai` + `xVerae-` + `attachPdf:true`
 
+## Signed macOS installer (.pkg)
+
+Same FlightLookup Developer ID + notarization path as Verae Timestamping.app (`~/fie/installers/macos/signing.env`).
+
+```bash
+cd /Users/marchon/research/PrintToVeraeTimeStamp
+chmod +x platform/macos/pkg/build-pkg.sh
+./platform/macos/pkg/build-pkg.sh
+# → build/macos-pkg/dist/VeraePrintStamp-0.1.0.pkg
+# → build/macos-pkg/dist/VeraePrintStamp-macos.pkg
+```
+
+The pkg installs:
+
+| Path | Role |
+|------|------|
+| `/Applications/Verae Print Stamp.app` | Drop / Open With |
+| `/Library/Application Support/Verae/PrintStamp/bin/verae-print` | Stamp CLI (universal) |
+| `/usr/local/bin/verae-print` | Symlink |
+| LaunchAgent + CUPS queue | **Print → Destination → Verae Timestamping** |
+
+Requires: `Developer ID Application` + `Developer ID Installer` (FlightLookup), App Store Connect API key in `signing.env`, Node for bundling the registration PDF builder.
+
 ## Status
 
-macOS v0 (PDF Services) is implemented. CUPS virtual printer, Linux, and Windows remain per the [spec](docs/superpowers/specs/2026-10-03-print-to-verae-timestamp.md) and [plan](docs/superpowers/plans/2026-10-03-print-to-verae-timestamp.md).
+macOS Destination printer + branded registration PDF work locally. Signed `.pkg` build script is under `platform/macos/pkg/`. Linux and Windows remain per the [spec](docs/superpowers/specs/2026-10-03-print-to-verae-timestamp.md) and [plan](docs/superpowers/plans/2026-10-03-print-to-verae-timestamp.md).
 
 ## Contributing