Refresh first-run welcome flow

[papi-ux]

Summary

• Reworks the first-run welcome into three concise Nova panels covering Polaris, Moonlight-compatible hosts, and handheld/TV play
• Adds controller/D-pad focusable actions for Discover hosts, Add manually, and Scan QR
• Wires the welcome QR action through the existing Nova QR scanner and keeps welcome_seen committed before navigation

User-facing impact

First launch now feels more polished and explains what Nova is for without overclaiming. Users can choose discovery, manual setup, or a Polaris pairing QR from the welcome screen with touch or controller navigation.

Test Plan

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

Notes

• QR copy is scoped to Polaris pairing QR because that path is already wired through NovaQrScanActivity.
• No device/runtime smoke was run for this card.

[papi-ux]

Closing this as superseded by #62. I pulled the welcome refresh into the Nova 1.1.0 release assembly branch, so keeping this separate PR open would duplicate that path.