[PATCH 11/14] lib-mail: Introduce struct message_part_data_limits and thread it throu...

[PATCH 11/14] lib-mail: Introduce struct message_part_data_limits and thread it through parsers

Add an empty struct message_part_data_limits and pass it by pointer through
message_part_data_parse_from_header() and message_part_envelope_parse_from_header().

No behaviour change: the struct has no fields yet and no limits are applied.
Subsequent commits add the individual limit fields and enforcement.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Gbp-Pq: Name 0011-lib-mail-Introduce-struct-message_part_data_limits-a.patch