fix: paint chart axes before overlapping series markers

[developer0hye]

Summary

Paint line/scatter axes and ticks before series so opaque markers cover overlapping axis rules, matching native Excel. Preserve all existing primitive geometry, paint, opacity and values; hollow and disabled markers keep the rule visible.

Related: #1578.

Testing

• The compiled-frame regression fails before the fix for opaque/hollow circles at two overlapping values and passes after it; disabled-marker controls retain the axis.
• cargo test --locked --workspace --no-fail-fast: 3,490 passed, 15 ignored. After updating to main 75d4046, cargo test --locked --workspace --lib passed 2,893 tests; all five two-page native probe outputs retain identical candidate paint traces.
• cargo clippy --locked --workspace --all-targets -- -D warnings, cargo fmt --all -- --check, and git diff --check passed.
• Five native Excel 16.112.3 cases: original, re-zip, red fill, no fill, disabled marker. All ten sheet PDFs passed integrity checks after recovering a final-quit AppleScript error; native/converter re-zip controls match. Every before/after paint primitive is preserved.
• Five-page 300-DPI audit: all 2,052 material clusters have explicit passing dispositions. Layout and text-layer reports preserve baseline findings; default extraction retains baseline table reading-order differences and eight extra space-census entries; pdftotext -layout has matching non-whitespace text.
• Documentation freshness review: PASS. See the evidence README and scripts/probes/issue-1578-marker-overlap.json for reproduction.

Visual impact

• No rendered PDF change
• Rendered PDF change or visual evidence added

Visual audit

• Issue: Charts: category-axis rule paints over an opaque series marker #1578
• Fixture: tests/fixtures/xlsx/issue_1181_fit_to_height.xlsx; marker-only variants in scripts/probes/issue-1578-marker-overlap.json
• Page(s): 1-5
• Renderer and DPI: pdftoppm, 300 DPI; native Excel 16.112.3
• Evidence mode: fix
• Layout audit report: assets/bugfixes/issue-1578/layout-audit.json
• Render cluster reports: assets/bugfixes/issue-1578/render-clusters-page-1.json, assets/bugfixes/issue-1578/render-clusters-page-2.json, assets/bugfixes/issue-1578/render-clusters-page-3.json, assets/bugfixes/issue-1578/render-clusters-page-4.json, assets/bugfixes/issue-1578/render-clusters-page-5.json
• Reference exporter differences: None
• Fine-detail threshold: 0.5pt
• Layout audit page count: Pass
• Layout audit text flow: XLSX: fitted fixed-row cell baselines sit up to 2.16pt above Excel on the budget sheet #1545, XLSX: wrapped Trebuchet MS 10pt lines advance 11.89pt instead of Excel’s 13pt #1551
• Layout audit visible fills: Pass
• Layout audit rectangle geometry: XLSX: an anchored chart's frame sits 12.4pt right of the native export's and 1.9% narrow #1272, XLSX: the Arial 18pt auto title row prints 28pt instead of Excel’s 24pt #1550
• Layout audit large shifts: Pass
• Layout audit fine shifts: XLSX: an anchored chart's frame sits 12.4pt right of the native export's and 1.9% narrow #1272, XLSX charts: fitted drawing foreground keeps the physical page origin #1542, XLSX: fitted fixed-row cell baselines sit up to 2.16pt above Excel on the budget sheet #1545, XLSX: the Arial 18pt auto title row prints 28pt instead of Excel’s 24pt #1550, XLSX: wrapped Trebuchet MS 10pt lines advance 11.89pt instead of Excel’s 13pt #1551, XLSX: a mixed-size Aptos footer remains 0.78pt above its native baseline #1552
• New follow-up issues found in this audit: Charts: series strokes drop declared round caps and joins #1590
• Model vision findings: Full five-page contexts, full-scale marker trios, axis-band crops and 5% pixel sweeps show the gray rule removed from opaque teal/red interiors and retained through hollow/disabled controls. All output pixels outside one axis row are unchanged; page 1 is wholly unchanged. Reviewed unchanged regions retain the explicit prior crop/cluster findings. Native marker bitmap edges remain softer; its cached-value origin is still XLSX: worksheet chart markers omit native raster placement #1577. The disabled control reveals round-cap/join loss Charts: series strokes drop declared round caps and joins #1590. Worksheet digits, font emphasis and hairlines remain legible in the final JPEG crops. All 2,052 material clusters are individually dispositioned; the new marker clusters remain tracked in XLSX: worksheet chart markers omit native raster placement #1577.
• GT: assets/bugfixes/issue-1578/gt.jpg
• Before: assets/bugfixes/issue-1578/before.jpg
• After: assets/bugfixes/issue-1578/after.jpg
• Native: None
• Compare: assets/bugfixes/issue-1578/compare.jpg

Visual comparison

GT	Before	After

Required inspection

• Rendered all evidence at 150 DPI or higher
• Stored progressive JPEG quality 86 assets with metadata stripped
• Used Codex/Claude vision to inspect the full GT/output pages, diff, and matched crops
• Inspected matched region crops at full resolution
• Ran compare_layout.py --audit --fine-shift PT and dispositioned every fine/large text-instance shift, rectangle geometry deviation, painted-text visibility mismatch, and visible-fill occlusion
• Ran compare_render.py --cluster-report PATH --strict-clusters and dispositioned every material 5% fuzz diff cluster by explicit ID
• Inventoried hairlines and border dash styles
• Inventoried font weight, italic, and underline emphasis

Deviation audit

Check	Result
Page count/order	Matches GT: original two sheets plus three deliberate marker probes
Element presence	Remaining: #1566 omitted worksheet separators. Marker-disabled control intentionally has no circle.
Position/size	Remaining: #1272 chart frame, #1542 drawing origin, #1543 fitted column width, #1545 row text, #1550 title height, #1552 footer, #1577 cached marker value.
Rotation/flip	No deviation observed
Fill	Fixed: opaque markers cover the category rule; hollow controls remain transparent.
Stroke/border	Remaining: #1564 worksheet rule thickness/placement, #1566 missing separators, #1590 series round caps/joins. Fixed: category rule paints underneath series. Gray chart axes, teal totals and brown expense rules retain paint; no new source dash loss.
Shape outline geometry	Remaining: #1272 chart frame, #1550 title band, #1590 series cap/join. Marker diameter and outline preserved.
Text content	Matches GT: non-whitespace sequence under pdftotext -layout; both contain narrow-cell ##### totals. Default extraction retains baseline table reading-order differences and eight extra space-census entries.
Font family/weight/style	Matches GT: Arial bold title, Trebuchet instructions/expense labels, Cambria headings/months and Aptos footer retain emphasis.
Text color	Matches GT: white title, teal headings/totals, gray body, orange negatives and brown expense labels.
Alignment	Remaining: #1542 drawing labels, #1545 row seating, #1550 title/content, #1552 footer, #1577 marker origin.
Line/paragraph spacing	Remaining: #1545 row seating and #1551 wrapped note pitch.
Clipping/overflow	No deviation observed beyond matching native narrow-cell ##### totals.

Checklist

• Commits include a Signed-off-by line
• PR scope contains one root cause
• Remaining converter or harness deviations each reference an open issue