v0.7.1

Fixes

• Gantt: the widest task label is no longer truncated (the margin was sized 2 columns short of its own content)
• Kanban: the widest card is no longer truncated (same off-by-two in column sizing); id[Title] cards with trailing @metadata now unwrap correctly
• CJK/emoji labels no longer overflow boxes or destroy borders in class, ER, gantt, kanban, packet, and treemap renderers; new shared truncate_to_width() helper never splits a wide character
• Sequence: self-messages reserve the rows they draw, so the next message's label no longer overwrites the loop's return arrow; CJK message labels are no longer clipped
• Block diagrams: blocks nested two or more groups deep are rendered instead of silently dropped