Bump grandiose pin to fix macOS arm64 build

[ktamas77]

Summary

The current grandiose pin (rse/grandiose#cf09bb84) lacks the mac && arm64 case in binding.gyp. As a result, on Apple Silicon grandiose.node builds without linking libndi, and the app SIGSEGVs on the first NDI call from the renderer.

rse/grandiose@456f3132 ("fix ARM64 usage") adds the missing case along with a separate ndi/lib/mac-a64/libndi.dylib. Bumping the pin is a one-line fix that makes electron-builder --mac --arm64 produce a working Vingester.app on Apple Silicon — no patches, no extra config.

What changes

-        "grandiose":                     "rse/grandiose#cf09bb84",
+        "grandiose":                     "rse/grandiose#456f3132ef60d068d989a208147d396596012dfb",

Verification

Locally tested on macOS 26.4 / Apple Silicon (M1 Pro):

• npm install — grandiose rebuilds cleanly via node-gyp 12; the new mac && arm64 case in binding.gyp correctly copies mac-a64/libndi.dylib into build/Release/ and links -lndi.
• npx electron-builder --mac --arm64 — produces dist/mac-arm64/Vingester.app.
• otool -L confirms grandiose.node now resolves @rpath/libndi.dylib (previously: no libndi dependency at all).
• App launches: main + GPU/renderer/network/audio helpers all start; AppleScript tell application "Vingester" to return version returns 2.8.0. No crash.

What this does NOT change

• Existing macOS x64, Windows, and Linux builds. The bumped grandiose still has all original platform cases (win-x64, lnx-x64, mac-x64, etc.) plus the new mac-a64.
• No source-code changes anywhere else in Vingester. vingester-ffmpeg.js already handles arch === "arm64" via @rse/ffmpeg.

Notes for the maintainer

• The pin is a full SHA, matching the existing style in this file.
• I had to use a recent node-gyp (12.x) on the build host because the bundled one in older electron-rebuild is incompatible with Python 3.12+. Not part of this PR — purely a build-host concern.