Conditional formatting: icon thresholds with ">" (gte="0")

[iluebbe]

Fixes #1160: icon set thresholds with ">" were evaluated as ">=".

Problem

In Excel, each icon threshold is ">=" (the default) or ">". The file stores ">" as gte="0" on the threshold's cfvo. GridCraft ignored gte, so a value exactly on a ">" threshold got the next higher icon. Saving the file then dropped the gte.

Measured in Excel for Microsoft 365, 3 Traffic Lights over 0…10:

Thresholds	Value	Excel	GridCraft before	GridCraft now
Number > 3, > 6	3	red	yellow	red
	6	yellow	green	yellow
Percent > 30, > 70	3	red	yellow	red
	7	yellow	green	yellow

Fix

• Model: CfRule::IconSet gets greater: Vec<bool>, one flag per threshold (same index as thresholds). It has a serde default, and an empty list means every threshold is ">=", so existing rules and saved state are unchanged.
• XLSX:
  • the reader takes gte from each cfvo;
  • the writer writes gte="0" where a flag is set, also when the lower bound is left out and gets prepended.
• Evaluation (cf.rs): compares with > where the flag is set.
• Command: home.conditionalFormat takes icon thresholds, which it had no parameter for: {"type": "iconSet", "thresholds": [{"type": "num", "value": 3, "operator": ">"}, …]}. List them from the lowest up, one per icon after the first; one per icon with the lower bound first, as in the file, works too.

Testing

• icon_thresholds_with_greater_than (engine): the table above, plus ">=" for comparison, through the command.
• icon_set_greater_than_thresholds_roundtrip (xlsx): gte="0" is written on the right cfvo and read back.
• full_roundtrip: its icon set now carries ">" thresholds and still compares equal.
• Excel: a file this branch wrote with > 3 and > 6 opens with IconCriteria(2..3).Operator = xlGreater.
• cargo xtask ci: fmt, clippy, test, assets, layers and wasm pass.
  • parity and keytips report their generated files out of date on this Windows checkout (core.autocrlf).
  • Regenerating them changes only line endings: git diff is empty, as on main.

Conflicts: #781 also adds a field to CfRule::IconSet, so whichever PR lands second needs a one-line merge.

The New Formatting Rule dialog (#1202, fixes #1165) builds on this branch, so this PR should merge first.

🤖 Generated with Claude Code

https://claude.ai/code/session_01SAgnkqJiy3v24Hp25dQLRj

[iluebbe]

Closing this pull request. #1160 describes the problem; its new comment adds the fix approach and Excel's read-back.