[helenanova]

Problem

Files generated by HwpWriter were rejected by Hancom Office with "파일이 손상되었습니다" (file is corrupted) even for a minimal document (#4).

Root causes

The writer emitted structurally invalid HWP 5.0 output in several independent ways:

• Missing \005HwpSummaryInformation stream
• FaceName record didn't follow spec 4.1.4 (truncated panose, extra substitute byte, wrong flags)
• CharShape referenced face name IDs in language categories with no registered face names
• TabDef missing its count field; ParaShape 58 bytes instead of 54
• CommonControl headers (tbl , gso ) missing the description BSTR (HWP 5.0.0.5+)
• Table body and cell list headers used wrong tag IDs (0x4F/0x4C instead of HWPTAG_TABLE 0x4D / HWPTAG_LIST_HEADER 0x48) and wrong internal layouts
• BorderFill dropped the color-pattern fill block on serialize
• Reader-side FaceName/TabDef/BorderFill parsing didn't match the spec either, so real files were misparsed

Fix

• Spec-compliant serialization for all of the above, verified byte-by-byte against a real Hancom-produced file (hwplib's blank.hwp)
• Face names are now tracked per language category (new FaceNameLanguage) so ID_MAPPINGS counts and CharShape references are always valid; new fonts register in all 7 categories
• \005HwpSummaryInformation property-set stream is written
• New HwpWriter::set_compressed() API; compressed output uses raw deflate (nowrap), matching hwplib and pyhwp

Testing

• 12 new regression tests in tests/writer_hancom_compat_test.rs assert the structural invariants of valid HWP 5.0 files
• Full suite: 162 tests pass
• Every writer example's output now parses cleanly with pyhwp (hwp5txt/hwp5html), including tables, images, and page layouts
• Round-trip: hwplib's blank.hwp parses and re-serializes into a clean file

Note: I don't have Hancom Office available in this environment, so compatibility is verified against pyhwp and a real Hancom-produced file rather than the application itself. A final smoke test of examples/create_document.rs output in Hancom Office would be appreciated.