Enhance GUI - #462

The GUI work here looks good to me — TaskStateCell, the currentToolName / taskStateText / isRunningWorker plumbing in Job.m, and the reworked XIB all read cleanly and match the title.

What I think needs flagging is that a second, much larger change is bundled in without being mentioned in the title or description:

• ARCHS = arm64 is hardcoded in 15 project files (imageoptim, libpng, libjpeg, oxipng, pngquant, zopfli-png, gifsicle, guetzli, advpng, jpegoptim, jpegtran, pngcrush, svgcleaner, plus release.xcconfig). That drops Intel Mac support entirely and would break upstream's universal release build.
• MACOSX_DEPLOYMENT_TARGET goes 10.15 → 13.0 in the same files.
• imageoptim/appcast.xml raises sparkle:minimumSystemVersion from 10.14.0 to 13.0.0. That's the live update feed — it would stop offering updates to existing users on older macOS.

Those are three separate policy decisions about who the app still supports, and they'd be easy to miss under "Enhance GUI" with an empty description. Splitting them into their own PR (or at least spelling them out) would make both halves much easier to review, and would let the GUI part land on its own merits.

For what it's worth, the deployment target does need to move: 10.15 is below what Xcode 26/27 accepts and the build fails outright on it — I filed #467 about that. But 12.0 is enough to satisfy Xcode, so 13.0 plus ARCHS = arm64 is a bigger cut than the build problem requires.