feat: add kotlin commands and skill pack

.cursor/rules/kotlin-coding-style.md

@@ -0,0 +1,36 @@
+---
+description: "Kotlin coding style extending common rules"
+globs: ["**/*.kt", "**/*.kts", "**/build.gradle.kts"]
+alwaysApply: false
+---
+# Kotlin Coding Style
+
+> This file extends the common coding style rule with Kotlin-specific content.
+
+## Formatting
+
+- **ktfmt** or **ktlint** are mandatory for consistent formatting
+- Use trailing commas in multiline declarations
+
+## Immutability
+
+- `val` over `var` always
+- Immutable collections by default (`List`, `Map`, `Set`)
+- Use `data class` with `copy()` for immutable updates
+
+## Null Safety
+
+- Avoid `!!` -- use `?.`, `?:`, `require`, or `checkNotNull`
+- Handle platform types explicitly at Java interop boundaries
+
+## Expression Bodies
+
+Prefer expression bodies for single-expression functions:
+
+```kotlin
+fun isAdult(age: Int): Boolean = age >= 18
+```
+
+## Reference
+
+See skill: `kotlin-patterns` for comprehensive Kotlin idioms and patterns.