fix(style): spacing directly represents blank lines between paragraphs (1 or 2)

src/style.rs

@@ -40,7 +40,7 @@ impl StyleProfile {
                 name: "宽松".into(),
                 alignment: TextAlignment::Left,
                 line_spacing: 1.0,
-                paragraph_spacing: 1.0,
+                paragraph_spacing: 2.0,
                 first_line_indent: 2.0,
                 font_size: 26.0,
             },
@@ -67,12 +67,13 @@ impl StyleProfile {
 }
 
 fn apply_para_spacing(text: &str, spacing: f32) -> String {
-    if spacing <= 0.0 {
-        return text.to_string();
+    let blank_lines = spacing.round().max(0.0) as usize;
+    if blank_lines == 0 {
+        return text.to_string(); // 保留 strip_html 输出的 \n\n，即 1 行空白
     }
-    // spacing 表示额外空白行数：基础换行 \n\n 已有1行空白，再加 spacing 行
-    let newlines = 2 + spacing.round().max(0.0) as usize;
-    let sep = "\n".repeat(newlines);
+    // spacing 直接表示段落间空白行数（1行=1空行，2行=2空行）
+    let total_nl = blank_lines + 1;
+    let sep = "\n".repeat(total_nl);
     text.replace("\n\n", &sep)
 }