feat(highcharts): implement bar-basic (#133)

## Summary
Implements `bar-basic` for **highcharts** library.

**Parent Issue:** #117
**Sub-Issue:** #125
**Base Branch:** `plot/bar-basic`
**Attempt:** 1/3

## Implementation
- `plots/highcharts/bar/bar-basic/default.py`

## Features
- Uses `ColumnSeries` for vertical bars (Highcharts terminology for bar
charts)
- X-axis with category labels
- Y-axis starting at zero with subtle dotted grid lines (alpha ~0.15)
- Customizable colors, opacity, rotation of labels
- Input validation for empty data and missing columns
- Google-style docstrings with Args, Returns, Raises, Example sections
- Selenium-based PNG export for testing

## Quality Criteria Met
- [x] X-axis displays category labels clearly
- [x] Y-axis shows numeric scale with appropriate tick marks
- [x] Both axes are labeled (custom or column names)
- [x] Grid lines visible but subtle on y-axis only
- [x] Bars have consistent width and spacing
- [x] Bar colors distinguishable from background
- [x] Title present when specified
- [x] Y-axis starts at zero

Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>

Author: claude[bot]

plots/highcharts/bar/bar-basic/default.py

@@ -0,0 +1,183 @@
+"""
+bar-basic: Basic Bar Chart
+Library: highcharts
+
+A fundamental vertical bar chart that visualizes categorical data with numeric values.
+
+Note: Highcharts requires a license for commercial use.
+"""
+
+from typing import Optional
+
+import pandas as pd
+from highcharts_core.chart import Chart
+from highcharts_core.options import HighchartsOptions
+from highcharts_core.options.series.bar import ColumnSeries
+
+
+def create_plot(
+    data: pd.DataFrame,
+    category: str,
+    value: str,
+    figsize: tuple[int, int] = (10, 6),
+    color: str = "steelblue",
+    edgecolor: str = "black",
+    alpha: float = 0.8,
+    title: Optional[str] = None,
+    xlabel: Optional[str] = None,
+    ylabel: Optional[str] = None,
+    rotation: int = 0,
+    width: int = 1600,
+    height: int = 900,
+    **kwargs,
+) -> Chart:
+    """
+    Create a basic bar chart from DataFrame.
+
+    Args:
+        data: Input DataFrame with categorical and numeric data
+        category: Column name for category labels (x-axis)
+        value: Column name for numeric values (bar heights)
+        figsize: Figure size as (width, height) in inches (legacy, use width/height instead)
+        color: Bar fill color
+        edgecolor: Bar edge color
+        alpha: Transparency level for bars (0.0 to 1.0)
+        title: Plot title
+        xlabel: X-axis label (defaults to column name if None)
+        ylabel: Y-axis label (defaults to column name if None)
+        rotation: Rotation angle for x-axis labels
+        width: Figure width in pixels (default: 1600)
+        height: Figure height in pixels (default: 900)
+        **kwargs: Additional parameters passed to chart options
+
+    Returns:
+        Highcharts Chart object
+
+    Raises:
+        ValueError: If data is empty
+        KeyError: If required columns are not found in data
+
+    Example:
+        >>> data = pd.DataFrame({
+        ...     'category': ['A', 'B', 'C'],
+        ...     'value': [10, 20, 30]
+        ... })
+        >>> chart = create_plot(data, 'category', 'value', title='My Chart')
+    """
+    # Input validation
+    if data.empty:
+        raise ValueError("Data cannot be empty")
+
+    for col in [category, value]:
+        if col not in data.columns:
+            available = ", ".join(data.columns.tolist())
+            raise KeyError(f"Column '{col}' not found. Available: {available}")
+
+    # Create chart
+    chart = Chart()
+    chart.options = HighchartsOptions()
+
+    # Chart configuration
+    chart.options.chart = {"type": "column", "width": width, "height": height, "backgroundColor": "#ffffff"}
+
+    # Title
+    if title:
+        chart.options.title = {"text": title, "style": {"fontSize": "16px", "fontWeight": "bold"}}
+    else:
+        chart.options.title = {"text": None}
+
+    # X-axis configuration
+    categories = data[category].tolist()
+    x_label = xlabel if xlabel is not None else category
+    chart.options.x_axis = {
+        "categories": categories,
+        "title": {"text": x_label, "style": {"fontSize": "12px"}},
+        "labels": {"rotation": -rotation if rotation else 0, "style": {"fontSize": "10px"}},
+    }
+
+    # Y-axis configuration with subtle grid (y-axis only per spec)
+    y_label = ylabel if ylabel is not None else value
+    chart.options.y_axis = {
+        "title": {"text": y_label, "style": {"fontSize": "12px"}},
+        "min": 0,
+        "gridLineWidth": 1,
+        "gridLineDashStyle": "Dot",
+        "gridLineColor": "rgba(0, 0, 0, 0.15)",
+        "labels": {"style": {"fontSize": "10px"}},
+    }
+
+    # Create series with column type (vertical bars in Highcharts)
+    series = ColumnSeries()
+    series.data = data[value].tolist()
+    series.name = y_label
+    series.color = color
+    series.border_color = edgecolor
+    series.border_width = 1
+
+    # Set opacity via plot options
+    chart.options.plot_options = {
+        "column": {"opacity": alpha, "pointPadding": 0.1, "groupPadding": 0.1, "borderWidth": 1, "colorByPoint": False}
+    }
+
+    chart.add_series(series)
+
+    # Legend (single series, so hide legend)
+    chart.options.legend = {"enabled": False}
+
+    # Credits
+    chart.options.credits = {"enabled": False}
+
+    return chart
+
+
+if __name__ == "__main__":
+    import tempfile
+    import time
+    from pathlib import Path
+
+    from selenium import webdriver
+    from selenium.webdriver.chrome.options import Options
+
+    # Sample data for testing
+    sample_data = pd.DataFrame(
+        {"category": ["Product A", "Product B", "Product C", "Product D", "Product E"], "value": [45, 78, 52, 91, 63]}
+    )
+
+    # Create plot
+    chart = create_plot(
+        sample_data, "category", "value", title="Sales by Product", xlabel="Product Category", ylabel="Sales ($)"
+    )
+
+    # Export to PNG via Selenium screenshot
+    html_str = chart.to_js_literal()
+    html_content = f"""<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <script src="https://code.highcharts.com/highcharts.js"></script>
+</head>
+<body style="margin:0;">
+    <div id="container" style="width: 1600px; height: 900px;"></div>
+    <script>{html_str}</script>
+</body>
+</html>"""
+
+    # Write temp HTML and take screenshot
+    with tempfile.NamedTemporaryFile(mode="w", suffix=".html", delete=False) as f:
+        f.write(html_content)
+        temp_path = f.name
+
+    chrome_options = Options()
+    chrome_options.add_argument("--headless")
+    chrome_options.add_argument("--no-sandbox")
+    chrome_options.add_argument("--disable-dev-shm-usage")
+    chrome_options.add_argument("--window-size=1600,900")
+
+    driver = webdriver.Chrome(options=chrome_options)
+    driver.get(f"file://{temp_path}")
+    time.sleep(1)  # Wait for chart to render
+    driver.save_screenshot("plot.png")
+    driver.quit()
+
+    Path(temp_path).unlink()  # Clean up temp file
+    print("Plot saved to plot.png")