Eremey Valetov c736b19bae Fix single-file backward compatibility with original UC2 Pro ...

Root cause: the original UC2 Pro expects csize=0 in the cdir COMPRESS
record (it ignores the field entirely).  UC2 v3 was writing the actual
compressed size, which confused the original's archive reader.

Additional changes:
- Use default Huffman tree for all blocks (ensures tree encoding compat)
- Write method=compression_level in cdir COMPRESS (was hardcoded to 1)
- Add tests/scripts/bitdump.py for bit-level bitstream analysis

Single-file UC2 v3 archives are now fully readable by the original UC2
Pro (listing and extraction verified in DOSBox-X).  Multi-file archives
still hang — the cdir bitstream decodes correctly in our Python analyzer
but fails in the original's ASM decompressor kernel.  Investigation
continues; the bitdump.py tool enables targeted comparison.

2026-03-29 09:58:36 -04:00

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