Logs & JSON metadata

Log and JSON files use structure heuristics — not column statistics. Logs may still produce templates from line patterns.

`log_metadata`

Field	Meaning
`byte_count`, `line_count`	Size
`line_ending`	`lf`, `crlf`, or `cr`
`max_line_length`, `blank_line_count`	Line shape
`has_timestamps`	Heuristic: ISO8601 or Unix epoch on early lines

Field	Meaning
`byte_count`, `line_count`	Size
`line_ending`, `max_line_length`, `blank_line_count`	Line shape
`root_type`	`array` or `object`
`root_array_length`, `root_object_key_count`	Top-level size
`max_depth`	Nesting depth
`pretty_printed`	Heuristic from newlines after `{`, `[`, `,`