epic: align deps ndk

[ovitrif]

Goal

Align the Android NDK configuration used by Bitkit's owned Rust AAR dependencies with the Bitkit Android release toolchain, publish updated artifacts, and integrate them for Bitkit 2.6.0.

Target the app's currently pinned release NDK: r28b / 28.1.13356709.

Why

The owned Rust dependencies are currently built with different NDK configurations. There is no known runtime failure from this, but the configuration should be consistent across the repositories Bitkit controls.

This is a coordinated configuration task and is tracked separately from the R8 consumer-rules fix.

Audit trail

Audited on 2026-08-27:

• Bitkit Android's Justfile, stable release workflow, and internal release workflow pin NDK_VERSION=28.1.13356709.
• app/build.gradle.kts applies that value through AGP's ndkVersion.
• The locally generated Bitkit Core binaries reviewed in fix: android consumer-rules bitkit-core#145 were built with r28b.
• Published com.synonym:bitkit-core-android:0.5.9 was built with r28c.
• The LDK Node, VSS client, and Paykit publication workflows request r28c but leave the runner's r27d ANDROID_NDK_HOME conflicting with ANDROID_NDK_ROOT, so their published artifacts were built with r27d.

Relevant publication runs:

• LDK Node: https://github.com/synonymdev/ldk-node/actions/runs/32992410519
• VSS client: https://github.com/synonymdev/vss-rust-client-ffi/actions/runs/32992413948
• Paykit: https://github.com/pubky/paykit-rs/actions/runs/32993306274
• Bitkit Core: https://github.com/synonymdev/bitkit-core/actions/runs/32992320812

Scope

This epic covers:

• Aligning Bitkit Core's Android NDK configuration and publishing a new package.
• Aligning LDK Node's Android NDK configuration and publishing a new package.
• Aligning VSS Rust client FFI's Android NDK configuration and publishing a new package.
• Aligning Paykit's Android NDK configuration and publishing a new package.
• Integrating those package releases in Bitkit Android.

Third-party native dependencies such as JNA are out of scope because Bitkit does not control their toolchains.

The epic is complete when every repository-specific configuration change is merged, the new packages are published, and Bitkit Android consumes them.