fix: replace deprecated *ngIf with @if control flow in OTP component

- Migrated all *ngIf directives to modern @if syntax in otp.component.html
- Updated email form, OTP entry, countdown display, and success message conditionals
- Resolves ngtsc deprecation warning 6385 for better Angular 17+ compatibility

src/app/auth/otp/otp.component.html

@@ -0,0 +1,40 @@
+<div class="otp-container">
+    <h2>🔐 Email Verification</h2>
+
+    <!-- Step 1: Enter Email -->
+    @if (!isOtpSent()) {
+        <form [formGroup]="emailForm" (ngSubmit)="sendOtp()">
+            <label>Email Address</label>
+            <input type="email" formControlName="email" placeholder="Enter your email" />
+            <button type="submit" [disabled]="emailForm.invalid">Send OTP</button>
+        </form>
+    }
+
+    <!-- Step 2: Enter OTP -->
+    @if (isOtpSent() && !isVerified()) {
+        <div>
+            <p>OTP sent to <b>{{ emailForm.value.email }}</b></p>
+
+            <form [formGroup]="otpForm" (ngSubmit)="verifyOtp()">
+                <label>Enter 6-digit OTP</label>
+                <input type="text" maxlength="6" formControlName="otp" placeholder="123456" />
+                <button type="submit" [disabled]="otpForm.invalid">Verify OTP</button>
+            </form>
+
+            <button (click)="resendOtp()" [disabled]="countdown() > 0">
+                Resend OTP @if (countdown() > 0) {
+                    <span>({{ countdown() }}s)</span>
+                }
+            </button>
+        </div>
+    }
+
+    <!-- Step 3: Success -->
+    @if (isVerified()) {
+        <div>
+            <p class="success">✅ Your email has been verified successfully!</p>
+        </div>
+    }
+
+    <p class="message">{{ message() }}</p>
+</div>