Annotate StableHloConverterFactory for Java call sites (#400)

Adds `@JvmStatic` to every factory method on the
`StableHloConverterFactory` object (`createBasic`, `createExtended`,
`createFast`, `createCustom`) plus `@JvmOverloads` on `createCustom`
so every parameter default generates a separate JVM overload.

Before: Java call sites had to go through the Kotlin singleton
marker:

    var converter = StableHloConverterFactory.INSTANCE.createExtended();

After: Java callers can use the idiomatic static form:

    var converter = StableHloConverterFactory.createExtended();

The `@JvmStatic` annotation lives in `commonMain` — Kotlin 1.9+
accepts JVM-specific annotations in common code and treats them
as no-ops on non-JVM targets. Verified across all Kotlin
Multiplatform targets (jvmTest, wasmJsTest, wasmJsBrowserTest,
wasmWasiTest, wasmWasiNodeTest, macosArm64Test,
iosSimulatorArm64Test) — zero regressions.

Second of five commits polishing the Java / JVM consumption
story for the upcoming 0.19.0 release. See #400.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: michalharakal

skainet-compile/skainet-compile-hlo/src/commonMain/kotlin/sk/ainet/compile/hlo/StableHloConverterFactory.kt

@@ -9,6 +9,7 @@ import sk.ainet.compile.hlo.converters.MathOperationsConverter
 import sk.ainet.compile.hlo.converters.NeuralNetOperationsConverter
 import sk.ainet.compile.hlo.converters.ReductionOperationsConverter
 import sk.ainet.compile.hlo.converters.ShapeOperationsConverter
+import kotlin.jvm.JvmStatic
 
 /**
  * Factory for creating StableHLO converters with default configurations.
@@ -21,6 +22,7 @@ public object StableHloConverterFactory {
     /**
      * Create a converter with basic operations support (add, matmul, relu)
      */
+    @JvmStatic
     public fun createBasic(): StableHloConverter {
         val registry = StableHloOperationRegistry()
         val typeMapper = TypeMapper()
@@ -57,6 +59,7 @@ public object StableHloConverterFactory {
     /**
      * Create a converter with extended operations support
      */
+    @JvmStatic
     public fun createExtended(): StableHloConverter {
         val registry = StableHloOperationRegistry()
         val typeMapper = TypeMapper()
@@ -96,6 +99,7 @@ public object StableHloConverterFactory {
     /**
      * Create a converter without validation (for performance)
      */
+    @JvmStatic
     public fun createFast(): StableHloConverter {
         val registry = StableHloOperationRegistry()
         val typeMapper = TypeMapper()
@@ -115,6 +119,8 @@ public object StableHloConverterFactory {
     /**
      * Create a custom converter with the provided components
      */
+    @JvmStatic
+    @kotlin.jvm.JvmOverloads
     public fun createCustom(
         registry: StableHloOperationRegistry,
         typeMapper: TypeMapper = TypeMapper(),