fix: address Input component review feedback

- Remove incorrect placeholder color override in readonly state (lines 102-106)
  This was creating a CSS variable scoping issue where placeholder used
  the default color instead of readonly color
- Add test for readonly + invalid showing neutral appearance
- Add test for error icon hidden in readonly + invalid state

Addresses review feedback on PR #4531

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: millus

packages/eds-core-react/src/components/next/Input/Input.test.tsx

@@ -127,6 +127,15 @@ describe('Input (Next EDS 2.0)', () => {
       const errorIcon = container.querySelector('.eds-error-icon')
       expect(errorIcon).not.toBeInTheDocument()
     })
+
+    it('Does not show error icon when readOnly even if invalid', () => {
+      const { container } = render(
+        <Input invalid readOnly aria-label="ReadOnly invalid input" />,
+      )
+      // eslint-disable-next-line testing-library/no-container, testing-library/no-node-access
+      const errorIcon = container.querySelector('.eds-error-icon')
+      expect(errorIcon).not.toBeInTheDocument()
+    })
   })
 
   describe('Adornments', () => {
@@ -208,6 +217,12 @@ describe('Input (Next EDS 2.0)', () => {
         expect(wrapper).toHaveAttribute('data-color-appearance', 'neutral')
       })
 
+      it('Sets neutral appearance when readOnly regardless of invalid state', () => {
+        render(<Input invalid readOnly />)
+        const wrapper = getInputWrapper()
+        expect(wrapper).toHaveAttribute('data-color-appearance', 'neutral')
+      })
+
       it('Input element has correct font styling attributes', () => {
         render(<Input invalid value="test" readOnly />)
         const input = screen.getByDisplayValue('test')

packages/eds-core-react/src/components/next/Input/input.css

@@ -98,12 +98,6 @@
         color: var(--_readonly-text-color);
         /* Safari autofill override */
         -webkit-text-fill-color: var(--_readonly-text-color);
-
-        &::placeholder {
-          color: var(--_placeholder-text-color);
-          /* Safari autofill override */
-          -webkit-text-fill-color: var(--_placeholder-text-color);
-        }
       }
 
       & .eds-adornment__text,