[Feature] Clarify and standardize distance file import format

[antoinepatalano]

Distance File Import — Format Specification

When importing a distances file through the GUI, the following formats should be supported:

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1-column format (values only)

• Exactly 6 rows, one distance value per row
• Values must appear in this exact order: d12, d23, d34, d41, d13, d24
• An optional single header row is allowed (max 7 rows total)
• No label column is present, so order is mandatory

Example:

19.97
36.84
29.30
19.73
44.36
27.14

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2-column format (label + value)

• Exactly 6 data rows, each with a label and a numeric distance value
• An optional header row is allowed
• Order is not required — rows are matched by label and reordered internally
• Labels must be recognized in any of these formats:
  • d12 / D12
  • 12
  • 1-2
  • 1 2
  • 1,2
  • 1;2

Example:

d13, 44.36
d24, 27.14
d12, 19.97
d34, 29.30
d23, 36.84
d41, 19.73

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Accepted file extensions

.csv, .tsv, .xlsx, .xls, .xlsm, .ods

Validation rules

• All distance values must be numeric and non-negative
• Exactly 6 distance values are required
• Unknown or unrecognized labels should raise a clear error message