2/5 Bar rendering — 8-block bars + y-axis labels

[MohnDoe]

Parent

#6 — BarChart — reusable vertical bar chart component

What to build

Render actual bars from BarItem[] data using 8-block unicode precision (▁▂▃▄▅▆▇█). Each bar occupies a column of computed width, with 1-space gap between bars. Bar height proportional to value / maxValue, mapped to 8 equal-sized buckets per text row. Any positive value gets at least ▁.

Y-axis with auto-density (every 1st/2nd/3rd row based on height) and configurable yAxisSpacing override. Y-axis values formatted via formatValue callback (default: String(Math.round(v))). Range configurable via minValue/maxValue options (default: 0-based from data). Y-axis separator string configurable via yAxisSeparator (default: " │ ").

Acceptance criteria

• Bars rendered at correct proportional heights using ▁▂▃▄▅▆▇█
• Positive values always show at least ▁
• Zero values show empty column
• Y-axis auto-density adapts to chart height
• yAxisSpacing overrides auto-density
• yAxisSeparator overrides default
• formatValue callback formats y-axis tick labels
• minValue/maxValue clamp/expand the y-axis range

Blocked by

• 1/5 BarChart shell — frame, axes, empty state, caching #7