v0.3.4

• A plain stack declared YXC is accepted (positional Y/X no longer count as named axes).
• A declaration that differs from the header only by swapping Y and X is accepted and read transposed (declared_axes_transposed); any other disagreement is refused.
• New shared reader read_confirmed_design. Edits to the design file are refused, naming the row and column, when a repeat group is empty, NA-like or differs from another only by case, or when confirmed_on is not an ISO date (YYYY-MM-DD).