chore: replace deprecated Resources.getColor and Gradle space-assignment DSL

[devin-ai-integration]

Summary

No SDK bump needed — launchdarkly-android-client-sdk is already pinned to 5.13.2, the latest 5.x on Maven Central. This PR only clears deprecation warnings that the build currently emits.

Two deprecations fixed:

• Resources.getColor(int) (deprecated since API 23) → ContextCompat.getColor(this, id) in MainActivity (5 call sites, both the initial render and the flag-change listener).
• Groovy DSL space assignment in app/build.gradle, which Gradle 9 warns "will fail with an error in Gradle 10":

  - namespace "com.launchdarkly.hello_android"
  - compileSdk 37
  + namespace = "com.launchdarkly.hello_android"
  + compileSdk = 37

  (also applicationId, versionCode, versionName, minifyEnabled, source/targetCompatibility)

One remaining Gradle 9 deprecation ("Using a Project object as a dependency notation") originates inside the Android Gradle Plugin, not this repo's scripts, so it is not actionable here.

How verified

• ./gradlew clean assembleDebug — BUILD SUCCESSFUL, and both the Kotlin getColor warnings and the namespace space-assignment warning are gone (verified with --warning-mode all).
• Installed the debug APK on an Android 36 x86_64 emulator with the hello-apps mobile key injected locally (never committed) and launched it; the app initialized the SDK and rendered the flag evaluation, confirming the ContextCompat.getColor styling path works at runtime:

Link to Devin session: https://app.devin.ai/sessions/7a61003c1e984050ad12233068fab8a3

---

Note

Low Risk
Mechanical deprecation fixes in sample app build config and UI coloring with no auth, data, or SDK version changes.

Overview
Clears build and Kotlin deprecation warnings without changing SDK version or app behavior.

app/build.gradle switches Android/Groovy properties from space assignment to = (namespace, compileSdk, applicationId, versionCode, versionName, minifyEnabled, sourceCompatibility, targetCompatibility) so Gradle 9+ stops warning about Gradle 10 breakage.

MainActivity.kt replaces five resources.getColor(...) calls with ContextCompat.getColor(this, ...) for initial flag UI styling and the real-time flag listener backgrounds, and adds the androidx.core.content.ContextCompat import.

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[devin-ai-integration]

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