fix(android): prevent date offset overflow

[marandaneto]

💡 Motivation and Context

PostHogAndroidDateProvider multiplied second offsets as an Int before adding them to a millisecond timestamp. Large offsets could overflow before being converted to Long, producing the wrong date.

This changes the multiplication to use Long arithmetic. It preserves the existing behavior for normal offsets and supports the full Int range accepted by the API.

💚 How did you test it?

• ./gradlew :posthog-android:testDebugUnitTest --tests "com.posthog.android.internal.PostHogAndroidDateProviderTest"
• make checkFormat
• Pi autoreview against origin/main

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran pnpm changeset to generate a changeset file

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Pi implemented the focused arithmetic fix and regression tests after a human-directed Slopo duplication review. Pi autoreview checked the committed branch and reported no actionable findings. The implementation keeps the existing Int API and changes only the intermediate multiplication type.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "fix(android): prevent date offset overfl..." | Re-trigger Greptile}