Plops editor: focus mode, place/move/resize, semantic zoom (#15)

Co-authored-by: Steve Dudenhoeffer <[email protected]>

web/src/editor/shared.ts

@@ -0,0 +1,14 @@
+// Shared editor UI constants + tiny helpers used across the object/plop markers
+// and overlays, so colors, handle sizes, and the object-local transform stay in
+// one place instead of drifting between files.
+
+export const SELECT_COLOR = '#2f7a3e' // selection stroke/handles
+export const HANDLE_PX = 12 // on-screen size of a drag/resize handle
+export const MIN_RADIUS_CM = 1 // smallest plop radius
+export const DIMMED_OPACITY = 0.4 // non-focused objects/plops in focus mode
+
+/** SVG transform placing content in an object's local frame: its center point
+ *  then its clockwise rotation. Plops and overlays render inside this. */
+export function objectTransform(o: { xCm: number; yCm: number; rotationDeg: number }): string {
+  return `translate(${o.xCm} ${o.yCm}) rotate(${o.rotationDeg})`
+}