Ship the LLVM libc++ license, document why the OpenHarmony PDFium component bundles libc++_shared.so, and record the pinned source-build compatibility patch and CI workflow.
Add build-pdfium-source.sh for the OHOS PDFium port at a pinned source revision, using the local SDK through the port's ohos_sdk/18 path and staging a stripped libpdfium.so plus its license. Keep the checksum-pinned prebuilt as an offline fallback and package the source license when present.
Strip the staged native libraries for release builds (PDFium 62 MB -> 22 MB), package THIRD_PARTY_NOTICES.md plus the repository license texts under resources/rawfile, and document the pinned OHOS PDFium archive and its remaining reproducible-build limitation.
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