Proposal: Terminal charts library (charm-charts)

## Problem

Building dashboards and data visualizations in Bubble Tea requires either:
- External libraries (termui, ntcharts) that don't integrate with lipgloss styling
- Manual Unicode block character manipulation
- No official solution from the Charm ecosystem

With the rise of CLI dashboards (lazydocker, k9s, btop), there's clear demand for chart components.

## Proposed Solution

**charm-charts** — terminal chart components styled with lipgloss.

### Sparkline
```go
data := []float64{4, 2, 7, 3, 8, 5, 9, 1, 6}
spark := charmcharts.NewSparkline(data).
Width(30).Height(3).
Style(lipgloss.NewStyle().Foreground(lipgloss.Color("212")))
// ▃▁▆▂▇▄█ ▅
```

### Bar Chart
```go
chart := charmcharts.NewBarChart(labels, values).
Width(50).Horizontal().
BarStyle(lipgloss.NewStyle().Foreground(lipgloss.Color("99")))
// Go ████████████████████ 85.0
// Rust ████████████████ 72.0
// Python ████████████████████████ 95.0
```

### Progress Bar
```go
bar := charmcharts.NewProgressBar(0.73).Width(30).Label("Upload")
// Upload ██████████████████████░░░░░░░░ 73%
```

### Features
- **Sparkline** — 1-8 row height, auto-scaling, data resampling
- **Bar Chart** — horizontal/vertical, labels, value display
- **Progress Bar** — custom fill/empty chars, percentage display
- Fluent builder API, lipgloss styling, charm-themes integration

## Working POC

https://github.com/junhinhow/charm-charts

Bilingual docs (EN/PT-BR).

## Questions

1. Would charts fit as a bubbles component or standalone package?
2. Interest in a Bubble Tea \`Model\` variant for real-time updating charts?
3. Should pie charts and line charts be added?