build(native-cpu): add publishing config + register in BOM

Layers the publishing setup that PR 1 of the native-FFM rollout
deliberately deferred (#571) onto the now-shipped scaffolding +
kernels. Lets downstream consumers pull the native provider through
the same coordinate-driven path the rest of the SKaiNET libraries
use, and lets a composite-build consumer (e.g. SKaiNET-transformers
via includeBuild) substitute the published coordinates with a local
project ref.

Changes:

- skainet-backends/skainet-backend-native-cpu/build.gradle.kts:
  add `alias(libs.plugins.vanniktech.mavenPublish)` to the plugins
  block. The vanniktech plugin auto-derives Maven coordinates from
  the root group (`sk.ainet.core`), version (`VERSION_NAME` —
  currently 0.22.0-SNAPSHOT), and the new gradle.properties below.

- skainet-backends/skainet-backend-native-cpu/gradle.properties: NEW.
  POM_ARTIFACT_ID=skainet-backend-native-cpu and POM_NAME mirroring
  the convention every other publishable module uses.

- skainet-bom/build.gradle.kts: add
  `api(project(":skainet-backends:skainet-backend-native-cpu"))`
  alongside the existing backend-api / backend-cpu constraints, so
  consumers depending on the BOM get a constrained version of the
  native module without adding a separate version pin.

Verification:

- ./gradlew :skainet-backends:skainet-backend-native-cpu:publishToMavenLocal
  -PRELEASE_SIGNING_ENABLED=false -PsignAllPublications=false
  publishes sk.ainet.core:skainet-backend-native-cpu-jvm:0.22.0-SNAPSHOT
  to ~/.m2 alongside the existing backend artifacts.

- ./gradlew publishToMavenLocal (full repo) — green, no regressions
  in the existing modules' publish tasks.

The native module's JAR carries the host-arch shared library at
native/<os>-<arch>/libskainet_kernels.{so|dylib|dll}, so a JAR
published from this build host (linux-x86_64 here) only carries the
linux-x86_64 .so. Multi-arch fat-JAR aggregation across the PR 4
cross-arch CI matrix runners is still deferred — consumers on other
arches cleanly fall back to the priority-50 Panama provider when
the native lib doesn't load.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: michalharakal

skainet-backends/skainet-backend-native-cpu/build.gradle.kts

@@ -1,5 +1,6 @@
 plugins {
     alias(libs.plugins.kotlinMultiplatform)
+    alias(libs.plugins.vanniktech.mavenPublish)
 }
 
 kotlin {

skainet-backends/skainet-backend-native-cpu/gradle.properties

@@ -0,0 +1,2 @@
+POM_ARTIFACT_ID=skainet-backend-native-cpu
+POM_NAME=skainet native (FFM) CPU kernel provider

skainet-bom/build.gradle.kts

@@ -18,6 +18,12 @@ dependencies {
         // Backend abstraction + CPU backend
         api(project(":skainet-backends:skainet-backend-api"))
         api(project(":skainet-backends:skainet-backend-cpu"))
+        // Native (FFM) priority-100 kernel provider — bundles a
+        // libskainet_kernels shared library and overrides the
+        // priority-50 Panama kernels for Q4_K and FP32 matmul on
+        // hosts where the native lib resolves. Cascades to Panama
+        // otherwise (missing arch, sandbox, kill-switch).
+        api(project(":skainet-backends:skainet-backend-native-cpu"))
 
         // IO modules
         api(project(":skainet-io:skainet-io-core"))