fix: prevent number input reset to 0 when clearing value in rule form

Avoid converting empty string to 0 in value1 and value2 number inputs, which caused unexpected behavior in some browsers when users cleared the field.

src/components/alert-settings/RuleFormCard.tsx

@@ -98,7 +98,14 @@ export function RuleFormCard({ rule, index, totalRules, onUpdate, onRemove }: Ru
                             type="number"
                             step="0.01"
                             value={rule.value1}
-                            onChange={(e) => onUpdate(index, { value1: Number(e.target.value) })}
+                            onChange={(e) => {
+                                const val = e.target.value
+                                // Only update if value is not empty; otherwise keep previous value
+                                // to avoid Number('') → 0 breaking the input in some browsers
+                                if (val !== '') {
+                                    onUpdate(index, { value1: Number(val) })
+                                }
+                            }}
                             className="w-full px-3 py-2 pl-10 bg-white border border-orange-200 rounded-lg text-sm font-medium focus:ring-2 focus:ring-orange-500 focus:border-orange-500"
                             placeholder={needsMax ? 'از' : 'مقدار'}
                             required
@@ -115,7 +122,14 @@ export function RuleFormCard({ rule, index, totalRules, onUpdate, onRemove }: Ru
                                     type="number"
                                     step="0.01"
                                     value={rule.value2 ?? ''}
-                                    onChange={(e) => onUpdate(index, { value2: Number(e.target.value) })}
+                                    onChange={(e) => {
+                                        const val = e.target.value
+                                        // Only update if value is not empty; otherwise keep previous value
+                                        // to avoid Number('') → 0 breaking the input in some browsers
+                                        if (val !== '') {
+                                            onUpdate(index, { value2: Number(val) })
+                                        }
+                                    }}
                                     className="w-full px-3 py-2 pl-10 bg-white border border-orange-200 rounded-lg text-sm font-medium focus:ring-2 focus:ring-orange-500 focus:border-orange-500"
                                     placeholder="تا"
                                     required