feat: Add 1/x inversion function to operators menu

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

calculator/calculator.app.js

@@ -56,6 +56,7 @@ if (process.env.HWVERSION!=1) {
   operators['='].grid = [1, 3];
   operators.r = {grid: [0, 2], val: 'sqrt'};
   operators.s = {grid: [1, 2], val: 'x^2'};
+  operators.i = {grid: [0, 3], val: '1/x'};
 }
 
 var specialsGrid = [2, 2];
@@ -341,6 +342,16 @@ function buttonPress(val) {
       }
       hasPressedNumber = false;
       break;
+    case 'i':
+      if (results != null) {
+        results = divide(1, results);
+        displayOutput(results);
+      } else if (currNumber != null) {
+        currNumber = divide(1, currNumber);
+        displayOutput(currNumber);
+      }
+      hasPressedNumber = false;
+      break;
     case 'N':
       if (results != null) {
         displayOutput(results *= -1);