Improve History Graph Layout & Dual Axis support and more ?

[penguin-fr]

I’d like to suggest a few possible improvements to the built-in History view and graphs, to make them more flexible and insightful.

🖼️ 1. Dynamic Graph Layout

When only one entity or several with same unit is selected in the History view, the chart currently occupies just a small portion of the screen (about 1/3 height on desktop).
It would be nice to have either:

• A dynamic layout that adjusts the graph height based on the number of entities shown
• And/Or a manual option to resize graph sections for better readability

This would help to have better visibility.

📈 2. Dual Y-Axis Support

Sometimes we need to compare two values with different units (e.g., °C and %, or W and V).
Currently, we can't put them on the same chart.

Adding a second Y-axis on the right (with automatic or manual mapping) would allow meaningful comparisons.

🤔 Not a Priority, But Still Worthwhile

Of course, this is not a priority, especially since we can achieve similar things using external tools like Grafana.
However, I believe that giving the native History view a visual and functional refresh would make Home Assistant feel even more polished out-of-the-box — especially for less technical users or quick insights.