perf(web): zero-copy pixel path + consolidate js/wasmJs into webMain#2
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Write pdfium's pixel ArrayBuffer straight into Skia's wasm linear memory (via Data.makeUninitialized + Int8Array.set on awaitSkiko's memory buffer, pattern from coil3.decode.WebWorker), removing the intermediate Kotlin ByteArray + installPixels copy. One memcpy on the main thread instead of two. Also consolidate the js + wasmJs sources into a shared webMain: - PdfDocument, PdfiumGlue externals, ClipEntryText, and the Skiko zero-copy helper all live in webMain - jsMain/wasmJsMain reduced to a ~30-line PlatformBridge covering the three structural differences between the targets: typed-array to Kotlin primitive conversion (zero-cost unsafeCast on js vs bulk copy on wasmJs), the kotlinx.coroutines.await signature mismatch (papered over by an awaitTyped<T>() expect/actual), and Skiko's platform- specific awaitSkiko - pdfium js target switched to useEsModules() so a single @jsmodule annotation works for both targets without a jsMain-only @JsNonModule
…specifics Expand README to include clarification on web zero-copy rendering via Skia's wasm heap and the use of `Data.makeUninitialized`. Consolidate and refine platform-specific implementation details for `jvmMain`, `androidMain`, `iosMain`, and `webMain`.
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Summary
ArrayBuffertransferred back from the pdfium worker is now written straight into Skia's wasm linear memory viaData.makeUninitialized+Int8Array.seton the buffer returned byorg.jetbrains.skiko.wasm.awaitSkiko. Pattern lifted from coil3.decode.WebWorker. One main-thread memcpy instead of two (dropped the intermediate KotlinByteArray+installPixelscopy).jsMain+wasmJsMainintowebMain: thePdfDocumentactual, thepdfium_glue.mjsexternals,ClipEntryText, and the Skiko zero-copy helper are now shared. Each leaf target keeps a ~30-linePlatformBridgethat covers only the genuine structural differences — typed-array conversion,kotlinx.coroutines.awaitsignature mismatch, and Skiko's platform-specificawaitSkiko.useEsModules()so a single@file:JsModule(\"./pdfium_glue.mjs\")declaration works for both targets without ajsMain-only@JsNonModulecompanion.Test plan
./gradlew :pdfium:compileKotlinJs :pdfium:compileKotlinWasmJspasses../gradlew :example:jsBrowserDevelopmentExecutableDistribution :example:wasmJsBrowserDevelopmentExecutableDistributionproduces a working bundle for both targets.