Fix soft line break issue in blockquote test case and paragraph processing

Co-authored-by: DongyuZhao <8455725+DongyuZhao@users.noreply.github.com>

Author: Copilot

Sources/CodeParserCollection/Markdown/Nodes/MarkdownParagraphBuilder.swift

@@ -81,13 +81,22 @@ public class MarkdownParagraphBuilder: MarkdownBlockBuilderProtocol {
       }
     }
 
-    // Only add separators if there's actual content and this line has content  
-    if !paragraph.children.isEmpty && !contentTokens.isEmpty && endsWithHardBreak {
-      // Only add hard line breaks - soft line breaks are implicit in AST
-      let lineBreakToken = createLineBreakToken("__HARD_LINE_BREAK__")
-      let lineBreakNodes = inlineProcessor.processInlineTokens([lineBreakToken])
-      for node in lineBreakNodes {
-        paragraph.children.append(node)
+    // Add line breaks for continuation lines if there's existing content and this line has content  
+    if !paragraph.children.isEmpty && !contentTokens.isEmpty {
+      if endsWithHardBreak {
+        // Add hard line break for lines ending with two spaces or backslash
+        let lineBreakToken = createLineBreakToken("__HARD_LINE_BREAK__")
+        let lineBreakNodes = inlineProcessor.processInlineTokens([lineBreakToken])
+        for node in lineBreakNodes {
+          paragraph.children.append(node)
+        }
+      } else {
+        // Add soft line break for regular continuation lines
+        let lineBreakToken = createLineBreakToken("__SOFT_LINE_BREAK__")
+        let lineBreakNodes = inlineProcessor.processInlineTokens([lineBreakToken])
+        for node in lineBreakNodes {
+          paragraph.children.append(node)
+        }
       }
     }
 

Tests/CodeParserCollectionTests/Markdown/Nodes/MarkdownBlockQuotesTests.swift

@@ -217,7 +217,7 @@ struct MarkdownBlockQuotesTests {
       """
     let result = parser.parse(input, language: language)
 
-    let expectedSig = "document[blockquote[paragraph[text(\"foo\"),text(\"bar\")]]]"
+    let expectedSig = "document[blockquote[paragraph[text(\"foo\"),line_break(soft),text(\"bar\")]]]"
     #expect(sig(result.root) == expectedSig)
   }