Add timeout cleanup to password reset confirm page and improve accessibility attributes

- Added `useEffect` for proper timeout cleanup in `PasswordResetConfirmForm` to prevent memory leaks during unmount.
- Enhanced form accessibility by adding `aria-required` attributes to all required fields for better screen reader compatibility.
- Updated `IMPLEMENTATION_PLAN.md` to reflect completion of Password Reset Flow and associated quality metrics.

frontend/src/components/auth/PasswordResetConfirmForm.tsx

@@ -210,6 +210,7 @@ export function PasswordResetConfirmForm({
                 ? 'new-password-error'
                 : 'password-requirements'
             }
+            aria-required="true"
           />
           {form.formState.errors.new_password && (
             <p id="new-password-error" className="text-sm text-destructive">
@@ -284,6 +285,7 @@ export function PasswordResetConfirmForm({
                 ? 'confirm-password-error'
                 : undefined
             }
+            aria-required="true"
           />
           {form.formState.errors.confirm_password && (
             <p id="confirm-password-error" className="text-sm text-destructive">

frontend/src/components/auth/PasswordResetRequestForm.tsx

@@ -157,6 +157,7 @@ export function PasswordResetRequestForm({
             {...form.register('email')}
             aria-invalid={!!form.formState.errors.email}
             aria-describedby={form.formState.errors.email ? 'email-error' : undefined}
+            aria-required="true"
           />
           {form.formState.errors.email && (
             <p id="email-error" className="text-sm text-destructive">