feat: expand component library with bar chart, content cards, and layout helpers

Add BarChart component that renders multi-row Unicode bar charts with
anchored Y-axis labels, automatic tick-step computation, sub-sampling
for narrow terminals, and optional X-axis date labels. The chart
gracefully degrades to a sparkline when width/height is too small.

Add ContentCard, CardRow, and CardInnerWidth utilities for consistent
bordered card layout across all dashboard tabs. ContentCard renders
a lipgloss-bordered card with optional bold title; CardRow joins
pre-rendered cards horizontally; CardInnerWidth computes the usable
text width after accounting for border and padding.

Add LayoutRow helper that distributes a total width into n integer
widths that sum exactly, absorbing the integer-division remainder
into the first items -- eliminates off-by-one pixel drift in multi-
column layouts.

Refactor MetricCard to accept an outerWidth parameter and derive the
content width internally by subtracting border, replacing the old
raw-width parameter that required callers to do the subtraction.
MetricCardRow now uses LayoutRow for exact width distribution.

Refine TabBar to render all tabs on a single row when they fit within
the terminal width, falling back to the two-row layout only when
they overflow.

Simplify StatusBar by removing the unused filterInfo append that was
cluttering the left section.

internal/tui/components/tabbar.go

@@ -70,7 +70,13 @@ func RenderTabBar(activeIdx int, width int) string {
 		parts = append(parts, rendered)
 	}
 
-	// Split into two rows if needed
+	// Single row if all tabs fit
+	full := " " + strings.Join(parts, "  ")
+	if lipgloss.Width(full) <= width {
+		return full
+	}
+
+	// Fall back to two rows
 	row1 := strings.Join(parts[:5], "  ")
 	row2 := strings.Join(parts[5:], "  ")