Package-level declarations

Rewrites every call to a log4k logging entry point so the emitted event carries a compile-time io.github.smyrgeorge.log4k.SourceLocation — the call's file, line, and enclosing function. Because the values are baked in as constants, accurate source locations cost no runtime stack-walking, and work uniformly on every Kotlin target (including Native, JS, and Wasm, where walking the stack is expensive or impossible).