Clip Path Generator

It generates `polygon()`: vertices are **percentage coordinates** (0–100 relative to the element itself), so one `clip-path` works on any size without recalculating pixels.

Dragging a vertex changes the shape (coordinates are clamped to 0–100), and the vertex order is the connection order — the wrong order gives a self-intersecting polygon, which is why dragging only moves points and never reorders them.

Six presets (triangle, rhombus, pentagon, hexagon, star, arrow) share state with the handles: once you drag, the preset stops being highlighted and Reset returns to it. Coordinates keep one decimal and drop a trailing `.0`, so the copied CSS reads like something you typed.