fix(FN-2838): prevent mobile zoom on dashboard form inputs

- Add global `touch-action: manipulation` on html/body to reduce gesture-triggered zoom
- Set mobile input font-size to 16px for terminal, nodes, and scripts modal form fields
- Extend mobile CSS regression tests to assert the global touch-action rule

packages/dashboard/app/styles.css

@@ -540,6 +540,7 @@ body {
   background: var(--bg);
   color: var(--text);
   overflow: hidden;
+  touch-action: manipulation;
 }
 
 #root {