Recursively walks a directory, identifies every file by 4-byte
magic, and reports per-format file count, total entries, and
bytes. Useful for content audits ("how many cinematics did
this asset bundle ship?") and for tracking migration progress
("what fraction of zones still lack a holiday catalog?").
Also extracts the format-magic table out of cli_info_magic.cpp
into a shared cli_format_table.{hpp,cpp} so --info-magic and
--summary-dir reuse the same source of truth — adding a new
format now updates one row in one file instead of two. Both
flags use the standard catalog header (magic + version + name
+ entryCount) for catalog formats; asset/world formats are
counted but report 0 entries since their headers differ.
Supports --json variant for tooling integration.
