Enhance Line Chart Examples with Interactive Tooltip Display for Basic and Smoothed Charts

The current Basic Line Chart and Smoothed Line Chart examples display static data but do not provide interactivity to view individual data points on click or hover.

Before:
. Basic Line Chart: [150, 230, 224, 218, 135, 147, 260]
.Smoothed Line Chart: [820, 932, 901, 934, 1290, 1330, 1320]

Problem:
Users cannot easily see the corresponding category (X-axis) and value (Y-axis) for each point on the line.

Suggested Enhancement:
-> Add tooltip with formatter to show the category and value when hovering or clicking on a point.
-> Apply this enhancement to both the basic and smoothed line chart examples.
-> This will make the examples more interactive and informative for developers learning ECharts.

No file or test paths are named. Locate the Basic Line Chart and Smoothed Line Chart examples, then inspect how each chart is configured. Done means both examples show the corresponding category and value in a tooltip when a point is hovered or clicked.

Written by the indexing model from the issue text.