Irregular polygons for LD2450 sensor

**Describe the problem you have/What new integration you would like**

I am working with the LD2450 wwMwave sensor and the esphome component is working well. However, one quite restrictive limitation is that the zones are limited to rectangles. I know from previous repositories that this isn't a necessary restriction. It would be most helpful if this could be enhanced to allow irregular polygons to build zones which match room shapes.

**Please describe your use case for this integration and alternatives you've tried:**

**Additional context**

Start by locating the ESPHome LD2450 component and its existing rectangle-zone configuration. Review how zones are represented and validated, then define what irregular polygon support should include and how completion would be verified; the request does not name files, tests, or an implementation entry point.

Written by the indexing model from the issue text.