feat(highcharts): implement line-basic

Implements the basic line plot specification for highcharts library.

- Uses LineSeries from highcharts-core
- Includes proper axis labels and title
- Uses Python Blue color (#306998) from style guide
- Targets 4800x2700 resolution as specified
- Exports to PNG via Selenium/headless Chrome

Author: github-actions[bot]

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

@@ -92,12 +92,16 @@
 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=4800,2700")
+chrome_options.add_argument("--window-size=4900,2800")
 
 driver = webdriver.Chrome(options=chrome_options)
 driver.get(f"file://{temp_path}")
 time.sleep(5)
-driver.save_screenshot("plot.png")
+
+# Capture the container element to get exact chart dimensions
+container = driver.find_element("id", "container")
+container.screenshot("plot.png")
+
 driver.quit()
 
 Path(temp_path).unlink()