Fix null safety bugs and resource leak

[dadachi]

Summary

• Fix FileOutputStream leak in shareImage() — use .use {} to guarantee stream closure on exception
• Fix potential crash in restartApp() — getLaunchIntentForPackage() can return null, replaced !! with ?: return
• Fix 6 instances of getData()?.id!! across 2 View files — replaced with safe ?.let {} pattern

Test plan

• ./gradlew assembleDebug passes
• ./gradlew test passes
• Manual: verify navigation still works from ShopSettings and ShopDetail screens

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