Migrate to Kotlin Multiplatform (Android, JVM, iOS)

[theshid]

Summary

Make PrettyLog callable from KMP commonMain so consumers don't have to gate logging behind their own expect/actual declarations or platform-specific source sets.

• Android consumers keep working unchanged via the published prettylog-android variant; existing call sites compile against the same Log.{d,i,w,e,wtf,network,timed}, PrettyLog.init, and LogBreadcrumbs.{record,getEntries,clear,dumpToFile} API.
• New: JVM + iOS targets (iosX64, iosArm64, iosSimulatorArm64) ship the same API.
• Version bumps to 0.2.0 to flag the binary-shape change.

What changed

Source layout — src/main → src/commonMain. Platform-touching code is extracted behind seams in commonMain:

• expect fun platformLog(...) — Logcat on Android, println on JVM, NSLog on iOS.
• expect fun resolveCallerInfo() — JVM stack walk shared by Android + JVM via a jvmCommonMain intermediate source set; returns null on iOS where Kotlin/Native lacks a portable equivalent (the bordered output simply omits the call-site header).
• expect helpers in Platform.kt for currentTimeMs(), currentThreadName(), and the HH:mm:ss.SSS log-timestamp format used by BreadcrumbEntry.formatted().

LogBreadcrumbs — buffer logic stays in commonMain; dumpToFile(Context) moves to androidMain as a top-level extension on the LogBreadcrumbs object so the existing call site (LogBreadcrumbs.dumpToFile(applicationContext)) compiles unchanged.

Three implementation choices worth flagging

1. ConcurrentLinkedDeque → ArrayDeque in the breadcrumb buffer. ArrayDeque is the only KMP-portable deque without pulling in kotlinx-atomicfu as a dep. Trade-off: high-concurrency logging may very rarely drop a single breadcrumb. Acceptable for a debug tool; if strict thread-safety becomes a requirement, the next move is kotlinx.atomicfu.locks.synchronized around the buffer ops.
2. kotlin.system.measureTimeMillis → kotlin.time.measureTimedValue in Log.timed. The original var result: T + assign-inside-lambda pattern is rejected by Kotlin/Native; measureTimedValue is the KMP-portable equivalent (still @OptIn(ExperimentalTime::class) in 1.9, stabilized in 2.0).
3. @kotlin.jvm.Volatile → @kotlin.concurrent.Volatile on PrettyLog.service. The latter is the KMP-portable annotation introduced in Kotlin 1.9.

Test plan

• ./gradlew :prettylog:assemble — Android AAR (debug + release), JVM JAR, all three iOS klibs compile cleanly
• ./gradlew :prettylog:publishToMavenLocal — produces the standard KMP publication: root metadata artifact prettylog + prettylog-android, prettylog-jvm, prettylog-iosx64, prettylog-iosarm64, prettylog-iossimulatorarm64
• Pull 0.2.0 into a downstream Android consumer and verify the existing call sites still link without changes
• Pull the iOS variant into a Compose Multiplatform sample to sanity-check NSLog output and the stack-trace-attached error path

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