Add PHOTON app icon

Native-drawn dark squircle with a cyan aperture/spark motif matching the
console's own color palette. Menu bar icon stays a plain SF Symbol by
design (colorful icons look muddy at that size); this is the Finder/Dock/
Get Info identity.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

PHOTON.app/Contents/Info.plist

@@ -10,6 +10,8 @@
     <string>PHOTON</string>
     <key>CFBundleDisplayName</key>
     <string>PHOTON</string>
+    <key>CFBundleIconFile</key>
+    <string>PHOTON.icns</string>
     <key>CFBundlePackageType</key>
     <string>APPL</string>
     <key>CFBundleShortVersionString</key>