mobile: cut home animation assets by 9.9 MB

[0xSero]

Purpose

Reduce the release weight of the two home-cat animations without changing their dimensions, frame count, cadence, transparency, or UI behavior. This is the first measured package reduction under #206.

What changed

• Re-encoded the 120-frame loop and 165-frame entrance animation as quality-90 animated WebP with transparent animation backgrounds and 67 ms frame cadence.
• Reused the same encoded assets on iOS and Android.
• Switched iOS bundle lookups and project.yml resources from APNG to WebP, then regenerated Litter.xcodeproj through make xcgen.

Size impact

Platform	Before	After	Reduction
iOS animation inputs	10,502,340 B	4,679,510 B	5,822,830 B (55.4%)
Android animation inputs	8,742,616 B	4,679,510 B	4,063,106 B (46.5%)
Tracked total	19,244,956 B	9,359,020 B	9,885,936 B

Fidelity checks

• Frame counts remain 120 and 165; canvas sizes remain 360x202 and 360x203.
• Animation background remains transparent and every frame duration is 67 ms.
• Sampled alpha masks are pixel-exact.
• Five sampled frames per animation measured 0.980-0.988 SSIM and 40.5-44.3 dB PSNR against the source APNGs.
• Side-by-side sampled-frame inspection found no visible edge, transparency, or pose regression.

Verification

• make xcgen
• ANDROID_SDK_ROOT=/Users/sero/Library/Android/sdk ANDROID_HOME=/Users/sero/Library/Android/sdk JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk-17.jdk ./gradlew :app:mergeDebugResources --no-daemon
• xcodebuild -project apps/ios/Litter.xcodeproj -scheme Litter -configuration Debug -destination 'platform=iOS Simulator,name=iPhone 17 Pro' -derivedDataPath /private/tmp/litter-assets-dd CODE_SIGNING_ALLOWED=NO build
• Installed that exact Litter.app into the iPhone 17 Pro simulator and launched com.sigkitten.litter; the home cat rendered with transparency and screenshots one second apart confirmed the animation advanced.

Android resource compilation is proven here; physical Android rendering remains for reviewer/device acceptance.