fix: add android r8 rules

[ovitrif]

Fixes #140

The Android AAR now ships targeted R8 consumer keep rules for the UniFFI/JNA FFI surface.

This is rebased on master after #138, at 0.5.9.

Description

• Packages bindings/android/lib/consumer-rules.pro into the AAR as proguard.txt.
• Keeps JNA Structure fields and constructors, Callback methods, and UniffiLib / IntegrityCheckingUniffiLib native method names in com.synonym.bitkitcore.
• Fails bundleReleaseAar when those consumer keep rules are missing or empty.
• Bumps the package to 0.5.9.

Preview

N/A — Android library packaging only.

QA Notes

Local verification: ./gradlew :lib:validateConsumerKeepRules :lib:bundleReleaseAar from bindings/android, then confirmed proguard.txt inside the release AAR.

[ovitrif]

version bump won't work until this PR is merged and bindings are rebuilt:

• feat: add Passport hardware wallet support #138

[ovitrif]

@ben-kaufman or @coreyphillips pls do a review even though it's merged, my AI was feeling too lucky today

[ben-kaufman]

The 0.5.9 release symbols no longer match the published Android AAR. The manual run published the immutable Maven package, then the release run rebuilt and replaced native-debug-symbols.zip before its Maven publish failed with 409. All four ABI build IDs differ. Could we restore the symbols from run 32992320812 and update the workflow so the AAR and symbols always come from one successful build?

[ovitrif]

Addressed the review concerns in:

• fix: android consumer-rules #145