fix(budget): strengthen print area grouping and suppress AppShell scrollbar (#1320)

[steilerDev]

Summary

• Added @media print override on .mainContent in AppShell.module.css to suppress the scrollbar area bleeding into print output — the CSS Module scoped class was not covered by the previous global overflow: visible rule
• Strengthened area row visual grouping in print output: bumped .rowLevel1 td top border to 3pt, applied var(--color-border) background tint (renders on paper), and set font-weight: 600 for semi-bold text

Fixes #1320

Test plan

• Print the Budget page and verify no scrollbar ghost column appears in the output
• Verify area rows (level 1) print with a visible top border, background tint, and semi-bold text
• Unit tests pass (95%+ coverage)
• Pre-commit hook quality gates pass

Co-Authored-By: Claude dev-team-lead (Sonnet 4.6) noreply@anthropic.com
Co-Authored-By: Claude frontend-developer (Haiku 4.5) noreply@anthropic.com

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