feat(ui): add Nova focus motion system

[papi-ux]

Summary

• Adds a shared Nova focus motion modifier for Compose cards, buttons, chips, and Polaris Library game cards.
• Adds animated scale, focus halo, border/color transitions, and pressed-state feedback for controller-friendly surfaces.
• Extends legacy app/server grid rows with animated focus scale and elevation so TV/handheld navigation feels more console-native.
• Adds source-guard coverage for the focus motion treatment.

Test Plan

• ./gradlew -PnovaAbis=x86_64 testNonRoot_gameDebugUnitTest
• ./gradlew -PnovaAbis=x86_64 testNonRoot_gameDebugUnitTest --tests com.papi.nova.ui.NovaFocusDrawableTest --tests com.papi.nova.ui.NovaComposeSourceGuardTest

Notes

• Not runtime/device-smoke tested yet.

[papi-ux]

Retroid smoke test for focus/motion polish:

• Device: Retroid Pocket 6, serial 24c12bdd
• Built: ./gradlew -PnovaAbis=arm64-v8a assembleNonRoot_gameDebug
• Installed: app/build/outputs/apk/nonRoot_game/debug/app-nonRoot_game-arm64-v8a-debug.apk
• Launched: com.papi.nova.debug/com.papi.nova.PcView
• Verified Library opened with 19 games from pc-papi.lan.
• D-pad focus moved from sidebar/filter area into a game card; focused card showed visible purple focus ring/halo and remained readable with no obvious clipping/overlap.
• Opened game detail sheet for Black Myth: Wukong; launch mode sheet rendered correctly and primary Launch Recommended button focus was visible/readable.
• Backed out to dashboard/server screen and exercised D-pad focus across dashboard actions; focus outlines remained visible and layout looked intact.
• Logcat check found no FATAL EXCEPTION / com.papi.nova.debug crash / ANR.

Not tested: actual stream launch/gameplay, reconnect/disconnect, long-run performance.