Add printable yard map and sprinkler zones with estimated coverage

README.md

@@ -124,3 +124,17 @@ of 24.
 
 - Decide whether parent-child feature relationships should further affect the visibility hierarchy.
 - If more data import is needed from GIS sources, prefer one-time extraction into JS-authored modules rather than making the app depend on runtime GIS tooling.
+
+### Sprinkler map
+
+`src/data/irrigation.js` contains the heads transcribed from the annotated printout,
+organized into visibility groups for zones 1–4. Positions, types, and coverage are
+initial estimates. Near the house, the head marked 2 is a zone 2 mist head;
+the adjacent head marked 4 is a zone 4 rotator. Each head has a stable zone/head ID.
+
+Head coordinates are authored in feet east and south of `lotCorner`. `reachFeet`
+is the spray radius. `startBearingDegrees` and `arcDegrees` describe a clockwise
+sector; the authoring helper converts lot-relative bearings to true bearings.
+Mist heads use a dotted fan symbol and dotted coverage; rotators use a sweep-arrow
+symbol and dashed coverage. Coverage and zone labels appear on screen and in print.
+Select a head to inspect its estimated dimensions and notes.