feat(highcharts): implement box-basic (#459)

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

**Parent Issue:** #204
**Sub-Issue:** #439
**Base Branch:** `plot/box-basic`
**Attempt:** 1/3

## Implementation
- `plots/highcharts/boxplot/box-basic/default.py`

## Changes
- Box plot with four groups (A, B, C, D) showing statistical
distributions
- Displays quartiles (Q1, median, Q3), whiskers (1.5×IQR), and outliers
- Uses Python Blue (#306998) for box fill and Signal Red (#DC2626) for
outliers and median line
- Proper 4800×2700 px output dimensions

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

Author: claude[bot]

plots/highcharts/boxplot/box-basic/default.py

@@ -139,13 +139,13 @@
 chrome_options.add_argument("--no-sandbox")
 chrome_options.add_argument("--disable-dev-shm-usage")
 chrome_options.add_argument("--disable-gpu")
-chrome_options.add_argument("--window-size=4900,2800")
+chrome_options.add_argument("--window-size=5000,3000")
 
 driver = webdriver.Chrome(options=chrome_options)
 driver.get(f"file://{temp_path}")
 time.sleep(5)
 
-# Take screenshot of the container element to get exact dimensions
+# Screenshot the container element for exact dimensions
 container = driver.find_element("id", "container")
 container.screenshot("plot.png")
 driver.quit()