CI: fix Android SDK cache restore permissions on Actions

[ggrell]

Summary

• move Android SDK cache to a writable runner path ($RUNNER_TEMP/android-sdk) instead of /usr/local/lib/android/sdk
• export ANDROID_SDK_ROOT and ANDROID_HOME to that writable location in all CI workflows
• install required SDK packages only when cache is missed (platform-tools, platforms;android-36, build-tools;36.0.0)
• bump cache key suffix to v2 to avoid stale cache reuse

Why

actions/cache restore into /usr/local/lib/android/sdk triggered repeated tar metadata errors (Cannot utime / Cannot change mode: Operation not permitted) on GitHub-hosted runners.

Expected impact

• no more noisy cache restore permission errors
• Android SDK is still cached between runs
• cache miss behavior remains explicit and deterministic

[github-actions]

	Messages
📖	JUnit: 27 tests, 0 failures/errors, 0 skipped.
📖	Static analysis summary: Detekt 0, Android Lint 0.

Generated by 🚫 Danger Kotlin against 91f05e4

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.11%. Comparing base (e48c425) to head (91f05e4).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #338   +/-   ##
=========================================
  Coverage     88.11%   88.11%           
  Complexity       50       50           
=========================================
  Files             9        9           
  Lines           101      101           
=========================================
  Hits             89       89           
  Misses           12       12           

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