feat: improve HTML text extraction with paragraph preservation, add reading margins, paragraph-aware pagination

src/reader.rs

@@ -160,14 +160,22 @@ pub fn reading_view(
 
     // --- Center text area ---
     egui::CentralPanel::default().show_inside(ui, |ui| {
-        let (rect, response) = ui.allocate_at_least(ui.available_size(), egui::Sense::click());
+        let available = ui.available_size();
+        let (rect, response) = ui.allocate_at_least(available, egui::Sense::click());
+
+        // Add reading margins (inset)
+        let inset = 24.0;
+        let text_rect = egui::Rect::from_min_size(
+            egui::pos2(rect.min.x + inset, rect.min.y),
+            egui::vec2((rect.width() - inset * 2.0).max(100.0), rect.height()),
+        );
 
         if let Some(section) = book.sections.get(*current_section) {
             if *current_page < section.pages.len().saturating_sub(1) {
                 let start = section.pages[*current_page];
                 let end = section.pages[*current_page + 1];
                 let text: String = section.content.chars().skip(start).take(end - start).collect();
-                ui.put(rect, |ui: &mut egui::Ui| {
+                ui.put(text_rect, |ui: &mut egui::Ui| {
                     ui.add(
                         egui::Label::new(
                             egui::RichText::new(&text)
@@ -242,15 +250,49 @@ pub fn calculate_pages(text: &str, chars_per_page: usize) -> Vec<usize> {
         return pages;
     }
 
-    let total_chars = text.chars().count();
+    let chars: Vec<char> = text.chars().collect();
+    let total_chars = chars.len();
     if total_chars <= chars_per_page {
         pages.push(total_chars);
         return pages;
     }
 
-    let mut pos = 0;
+    let mut pos: usize = 0;
     while pos < total_chars {
-        pos = (pos + chars_per_page).min(total_chars);
+        let next = pos + chars_per_page;
+        if next >= total_chars {
+            pages.push(total_chars);
+            break;
+        }
+
+        // Search backward from next for paragraph (\n\n) or line (\n) breaks
+        let search_start = pos + chars_per_page / 2;
+        let search_end = (next + chars_per_page / 2).min(total_chars);
+        let mut split = next;
+
+        // Prefer double newline (paragraph), then single newline
+        let mut found = false;
+        for i in (search_start..search_end).rev() {
+            if chars[i] == '\n' && i > 0 && chars[i - 1] == '\n' {
+                split = i - 1;
+                found = true;
+                break;
+            }
+        }
+        if !found {
+            for i in (search_start..search_end).rev() {
+                if chars[i] == '\n' {
+                    split = i + 1;
+                    break;
+                }
+            }
+        }
+
+        if split <= pos {
+            split = next;
+        }
+
+        pos = split.min(total_chars);
         pages.push(pos);
     }