fix(gateway): position cursor before placeholder in custom claim form

When a text field is empty, the cursor now appears before the placeholder
hint instead of after it, matching expected input behavior.

Author: aidandaly24

src/cli/tui/screens/mcp/AddGatewayScreen.tsx

@@ -1020,10 +1020,11 @@ function CustomClaimForm({ initialClaim, onSave, onCancel }: CustomClaimFormProp
       <Box marginTop={1} flexDirection="column">
         <Box>
           <Text color={activeField === 'claimName' ? 'cyan' : 'gray'}>Claim name: </Text>
+          {activeField === 'claimName' && !claimName && <Cursor />}
           <Text color={activeField === 'claimName' ? undefined : 'gray'}>
             {claimName || <Text dimColor>e.g., department</Text>}
           </Text>
-          {activeField === 'claimName' && <Cursor />}
+          {activeField === 'claimName' && claimName && <Cursor />}
         </Box>
 
         <Box>
@@ -1054,14 +1055,15 @@ function CustomClaimForm({ initialClaim, onSave, onCancel }: CustomClaimFormProp
 
         <Box>
           <Text color={activeField === 'matchValue' ? 'cyan' : 'gray'}>Match value: </Text>
+          {activeField === 'matchValue' && !matchValue && <Cursor />}
           <Text color={activeField === 'matchValue' ? undefined : 'gray'}>
             {matchValue || (
               <Text dimColor>
                 {valueType === 'STRING_ARRAY' ? 'comma-separated, e.g., admin, dev' : 'e.g., engineering'}
               </Text>
             )}
           </Text>
-          {activeField === 'matchValue' && <Cursor />}
+          {activeField === 'matchValue' && matchValue && <Cursor />}
         </Box>
       </Box>