feat: add kotlin commands and skill pack

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

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+---
+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.

.cursor/rules/kotlin-hooks.md

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+---
+description: "Kotlin hooks extending common rules"
+globs: ["**/*.kt", "**/*.kts", "**/build.gradle.kts"]
+alwaysApply: false
+---
+# Kotlin Hooks
+
+> This file extends the common hooks rule with Kotlin-specific content.
+
+## PostToolUse Hooks
+
+Configure in `~/.claude/settings.json`:
+
+- **ktfmt/ktlint**: Auto-format `.kt` and `.kts` files after edit
+- **detekt**: Run static analysis after editing Kotlin files
+- **./gradlew build**: Verify compilation after changes

.cursor/rules/kotlin-patterns.md

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+---
+description: "Kotlin patterns extending common rules"
+globs: ["**/*.kt", "**/*.kts", "**/build.gradle.kts"]
+alwaysApply: false
+---
+# Kotlin Patterns
+
+> This file extends the common patterns rule with Kotlin-specific content.
+
+## Sealed Classes
+
+Use sealed classes/interfaces for exhaustive type hierarchies:
+
+```kotlin
+sealed class Result<out T> {
+    data class Success<T>(val data: T) : Result<T>()
+    data class Failure(val error: AppError) : Result<Nothing>()
+}
+```
+
+## Extension Functions
+
+Add behavior without inheritance, scoped to where they're used:
+
+```kotlin
+fun String.toSlug(): String =
+    lowercase().replace(Regex("[^a-z0-9\\s-]"), "").replace(Regex("\\s+"), "-")
+```
+
+## Scope Functions
+
+- `let`: Transform nullable or scoped result
+- `apply`: Configure an object
+- `also`: Side effects
+- Avoid nesting scope functions
+
+## Dependency Injection
+
+Use Koin for DI in Ktor projects:
+
+```kotlin
+val appModule = module {
+    single<UserRepository> { ExposedUserRepository(get()) }
+    single { UserService(get()) }
+}
+```
+
+## Reference
+
+See skill: `kotlin-patterns` for comprehensive Kotlin patterns including coroutines, DSL builders, and delegation.

.cursor/rules/kotlin-security.md

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+---
+description: "Kotlin security extending common rules"
+globs: ["**/*.kt", "**/*.kts", "**/build.gradle.kts"]
+alwaysApply: false
+---
+# Kotlin Security
+
+> This file extends the common security rule with Kotlin-specific content.
+
+## Secret Management
+
+```kotlin
+val apiKey = System.getenv("API_KEY")
+    ?: throw IllegalStateException("API_KEY not configured")
+```
+
+## SQL Injection Prevention
+
+Always use Exposed's parameterized queries:
+
+```kotlin
+// Good: Parameterized via Exposed DSL
+UsersTable.selectAll().where { UsersTable.email eq email }
+
+// Bad: String interpolation in raw SQL
+exec("SELECT * FROM users WHERE email = '$email'")
+```
+
+## Authentication
+
+Use Ktor's Auth plugin with JWT:
+
+```kotlin
+install(Authentication) {
+    jwt("jwt") {
+        verifier(
+            JWT.require(Algorithm.HMAC256(secret))
+                .withAudience(audience)
+                .withIssuer(issuer)
+                .build()
+        )
+        validate { credential ->
+            val payload = credential.payload
+            if (payload.audience.contains(audience) &&
+                payload.issuer == issuer &&
+                payload.subject != null) {
+                JWTPrincipal(payload)
+            } else {
+                null
+            }
+        }
+    }
+}
+```
+
+## Null Safety as Security
+
+Kotlin's type system prevents null-related vulnerabilities -- avoid `!!` to maintain this guarantee.

.cursor/rules/kotlin-testing.md

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+---
+description: "Kotlin testing extending common rules"
+globs: ["**/*.kt", "**/*.kts", "**/build.gradle.kts"]
+alwaysApply: false
+---
+# Kotlin Testing
+
+> This file extends the common testing rule with Kotlin-specific content.
+
+## Framework
+
+Use **Kotest** with spec styles (StringSpec, FunSpec, BehaviorSpec) and **MockK** for mocking.
+
+## Coroutine Testing
+
+Use `runTest` from `kotlinx-coroutines-test`:
+
+```kotlin
+test("async operation completes") {
+    runTest {
+        val result = service.fetchData()
+        result.shouldNotBeEmpty()
+    }
+}
+```
+
+## Coverage
+
+Use **Kover** for coverage reporting:
+
+```bash
+./gradlew koverHtmlReport
+./gradlew koverVerify
+```
+
+## Reference
+
+See skill: `kotlin-testing` for detailed Kotest patterns, MockK usage, and property-based testing.