fix: build universal binary (arm64 + x86_64)

[beznazwiska]

Problem

build.sh hardcodes -target arm64-apple-macos13.0, producing an Apple Silicon-only binary. On Intel Macs the app fails to launch with:

bad CPU type in executable

The open command returns NSOSStatusErrorDomain Code=-10661, giving no clear indication that architecture is the root cause.

Solution

Build separate binaries for both architectures and merge them into a single universal binary via lipo:

swiftc -target arm64-apple-macos13.0 ...  → ClaudePeakHours_arm64
swiftc -target x86_64-apple-macos13.0 ... → ClaudePeakHours_x86_64
lipo -create *_arm64 *_x86_64 -output ClaudePeakHours

Additional improvements:

• Extracted source files and frameworks into variables (DRY)
• Added architecture info to build output for verification
• Cleaned up intermediate binaries after lipo

Testing

Verified on macOS 13.7 Ventura (Intel x86_64):

• build.sh completes successfully
• Output binary contains both architectures: Mach-O universal binary with 2 architectures: [x86_64] [arm64]
• App launches and runs correctly in menu bar
• No changes to Swift source code — build script only

Compatibility

• No breaking changes for Apple Silicon users
• install.sh works unchanged (calls build.sh internally)
• Pre-built releases would need to ship universal binaries separately