fix(stepper): add disabled state to prevent navigation and provide visual feedback

src/app/shared/components/stepper/stepper.component.ts

@@ -18,9 +18,12 @@ import { NgClass } from '@angular/common';
 export class StepperComponent {
   readonly steps = contentChildren(StepComponent);
   readonly initialStepIndex = input(0);
+  readonly disabled = input(false);
   readonly currentStepIndex = linkedSignal(() => this.initialStepIndex());
 
   next() {
+    if (this.disabled()) return;
+
     const currentSteps = this.steps();
     const currentIndex = this.currentStepIndex();
     if (currentIndex < currentSteps.length - 1) {
@@ -32,6 +35,8 @@ export class StepperComponent {
   }
 
   previous() {
+    if (this.disabled()) return;
+
     const currentIndex = this.currentStepIndex();
     if (currentIndex > 0) {
       this.currentStepIndex.set(currentIndex - 1);
@@ -39,6 +44,8 @@ export class StepperComponent {
   }
 
   goToStep(index: number) {
+    if (this.disabled()) return;
+
     const targetIndex = index;
     // Only allow navigating to completed steps or the current one
     if (targetIndex < this.currentStepIndex()) {