fix: markdown table row alignment

[chaehyun2]

Summary

• Switch table rendering from column-first to row-first layout (like HTML <tr>)
• Cells in the same row now share height naturally via flex row containers
• Add header row bottom border for visual separation
• Equal column widths via flex: 1 instead of content-dependent sizing
• minHeight: 40 prevents collapsed empty cells
• minWidth: 100% on table content ensures small tables fill container width
• Horizontal scroll indicator always visible (was hidden on web)

Changes

Single file: packages/happy-app/sources/components/markdown/MarkdownView.tsx (+44/-35)

Before (column-first): each column was a vertical container — cells in the same row could have different heights, and wide content clipped.

After (row-first): each row is a horizontal flex container — consistent row heights, proper text wrapping, clean borders.

Test plan

• Simple 3×3 table renders with aligned rows
• Long text in a cell wraps without clipping adjacent cells
• Empty cells render with consistent height (minHeight: 40)
• Wide tables (10+ columns) scroll horizontally
• Header row visually separated from data rows
• Tables with mixed content (bold, code, links) render correctly
• Single-column and single-row tables display properly

🤖 Generated with Claude Code
via Happy

[chaehyun2]

Closing — upstream rewrote the table rendering with dynamic column widths, spansLength() content-aware sizing, alignItems: 'stretch', and HorizontalScrollView. The alignment issues this PR addressed are fully resolved.