Prevent stale Magisk and KernelSU hooks from polling forever

[LIghtJUNction]

Summary

• preserve the existing 100 ms fast wait for the first 5 seconds, then fall back to one check per second
• remove both hooks when boot has completed and the device-protected LiveBoot launcher is still absent
• cap the fallback wait at 180 seconds so a boot that never completes cannot leave pollers alive for the entire uptime
• apply the same behavior to the duplicated Magisk and KernelSU hook paths
• add a script marker so existing unbounded hooks are detected and regenerated the next time LiveBoot is opened

The cleanup deliberately waits for sys.boot_completed rather than consulting PackageManager or parsing /data/system/packages.list during post-fs-data. At boot completion, device-protected storage should be available; before then, a missing files directory is not sufficient evidence that the app was uninstalled. If boot never completes, the hard timeout exits without deleting anything.

Fixes #24.

Testing

• ./gradlew :liveBootAni2:assembleDebug --stacktrace
  • passed on GitHub Actions: https://github.com/LIghtJUNction/liveboot/actions/runs/33110437993
• parsed all 15 Java source files successfully
• shellcheck -s sh and Android /system/bin/sh -n on the generated hook shape
• exercised the hook behavior with Android /system/bin/sh for:
  • launcher already present
  • launcher appearing during the fast wait
  • stale hook after boot completion (both hooks removed)
  • boot never completing (bounded exit without removal)

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