[sofialuiza15]

Improves naming in HexDump.dump(byte[], long, Appendable, int, int) and its private helpers. No behavior or public API change.

• chars_read -> bytesInLine (it counts bytes, nothing is "read" there)
• display_offset -> displayOffset (snake_case -> camelCase, as in the rest of the project)
• j -> lineStart, k -> column
• private dump(StringBuilder, byte) / dump(StringBuilder, long) -> appendHex(...), since they only append hex digits and shared a name with the public dump methods
• j -> digit in the helpers
• Javadoc of the helpers updated: appendHex(StringBuilder, long) now says it writes only the 32 least significant bits, which is what the code does.

Refactoring: Rename Variable / Rename Method. Only private members and local variables are touched, so binary compatibility is unaffected.

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  Claude Code (Claude Sonnet 5.5) made the code change and drafted this description; I reviewed it and ran the related tests.
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