Charts: a category axis' blanking c:numFmt (formatCode=";;") is ignored, so an axis Excel leaves empty prints 1, 2, 3

[developer0hye]

<c:catAx><c:numFmt formatCode=";;" sourceLinked="0"/> is a number format whose
three sections are all empty, which is Excel's way of printing nothing for a
positive, a negative or a zero value alike. A template uses it to keep an axis
whose labels would be meaningless from printing them. We never apply a category
axis' c:numFmt, so the labels print.

Measured

Monthly college budget1.xlsx (attached to #1123, committed as
tests/fixtures/xlsx/issue_1181_fit_to_height.xlsx), sheet Monthly college budget, xl/charts/chart1.xml — the january cash flow: bar chart. Its
category axis is not deleted, and it carries the blanking format:

<c:catAx><c:axId val="483691008"/><c:scaling><c:orientation val="minMax"/></c:scaling>
  <c:delete val="0"/><c:axPos val="l"/>
  <c:numFmt formatCode=";;" sourceLinked="0"/>
  <c:majorTickMark val="none"/><c:minorTickMark val="none"/>
  <c:tickLblPos val="nextTo"/>

The chart declares no <c:cat>, so the categories are the automatic 1..N.
Native Excel for Mac 16 export against our page 1, mutool draw -F trace,
printed points, y down from the page top:

instance	GT	ours
3	not drawn	x 613.09, baseline 195.97
2	not drawn	x 613.09, baseline 228.05
1	not drawn	x 613.09, baseline 260.14

The export draws no fill_text at all in that chart's category band; we draw
three digits down the left of its plot.

Reproduction

office2pdf --sheets "Monthly college budget" tests/fixtures/xlsx/issue_1181_fit_to_height.xlsx -o ours.pdf
mutool draw -F trace -o - ours.pdf 1 | grep -B 3 'unicode="3"'

Expected

A category axis whose c:numFmt formats every value to the empty string prints
no tick labels, and keeps whatever band the layout gives them.

Found while auditing #1182 on the same page; present before and after that fix.

[developer0hye]

Fixed by #1556, merged as 99ca7f0.

Rebuilt the CLI from clean merged main with cargo build --locked -p office2pdf-cli and freshly converted the public fixture with Excel's DFonts. Compared both printable sheets with the verified native Excel export: page 1 at 150 DPI and page 2 at 300 DPI, MuPDF layout audit at 0.5pt, text-layer comparison, full-page/diff inspection, and all 64 matched detail crops. The unwanted category digits 1, 2, and 3 are absent. Normalized layout-order text matches native on both pages. Fresh output is pixel-identical to the reviewed after renders, and the layout report is identical. All 552 material clusters retain explicit dispositions.

Remaining, tracked in #1185 (marker), #1270 (series no-fill), #1271 (gridline presence), #1272 (chart frame), #1274 (gridline opacity), #1542 (drawing placement), #1545 (row text), #1550 (title row), #1551 (wrapped note), and #1552 (footer). No new defect was found in this pass. The fixture as a whole still has these open defects.

PR checks passed. Merged-main CI run 33950793438 is still running at the time of this verification.

[developer0hye]

A subsequent full-resolution font/paint review corrected two earlier audit classifications. Cash-flow month labels use Cambria in native Excel but Trebuchet MS in output, now tracked in #1563. Fitted worksheet rules also differ in painted width and boundary placement, tracked in #1564. These are existing defects, not accepted antialiasing. The specific chart fix verified for this issue remains valid; the historical audit reports are being corrected in separate evidence changes.