Fix end_line for multi-line HTML blocks (types 1-5)

HTML blocks types 1-5 have explicit closing markers (</script>, -->,
?>, >, ]]>) that appear on the current line when the block is
finalized. This is structurally identical to fenced code blocks,
which were already handled by S_ends_on_current_line().

Without this fix, multi-line HTML blocks types 1-5 report end_line
as one less than the actual last line, because finalize() falls
through to the 'ended on previous line' case (line_number - 1).

Types 6-7 correctly continue to use line_number - 1 since they
end at a blank line (their last content is on the previous line).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: pboling

ext/markly/blocks.c

@@ -77,11 +77,25 @@ static CMARK_INLINE bool S_is_space_or_tab(char c) {
 // - Document node (special case)
 // - Fenced code blocks (end on the closing fence line)
 // - Setext headings (end on the underline)
-// - Any block finalized on the same line it started (e.g., single-line HTML blocks)
+// - HTML blocks types 1-5 per CommonMark spec §4.6 (end on the line
+//   containing the closing marker)
+// - Any block finalized on the same line it started (e.g., single-line blocks)
 static CMARK_INLINE bool S_ends_on_current_line(cmark_parser *parser, cmark_node *b) {
   return S_type(b) == CMARK_NODE_DOCUMENT ||
          (S_type(b) == CMARK_NODE_CODE_BLOCK && b->as.code.fenced) ||
          (S_type(b) == CMARK_NODE_HEADING && b->as.heading.setext) ||
+         // HTML block types per CommonMark spec §4.6:
+         //   1: <script>, <pre>, <style>, <textarea> (ends at </tag>)
+         //   2: <!-- (ends at -->)
+         //   3: <? (ends at ?>)
+         //   4: <! + letter (ends at >)
+         //   5: <![CDATA[ (ends at ]]>)
+         // All five end on the line containing their closing marker,
+         // similar to fenced code blocks.
+         // Types 6-7 end at a blank line, so their last content line is
+         // the previous line and they should NOT match here.
+         (S_type(b) == CMARK_NODE_HTML_BLOCK && b->as.html_block_type >= 1 &&
+          b->as.html_block_type <= 5) ||
          // Single-line blocks: finalized on same line they started
          b->start_line == parser->line_number;
 }

test/markly/node.rb

@@ -365,16 +365,14 @@
 		end
 
 		it "has correct position for multi-line HTML block" do
-			# Multi-line HTML comment (4 lines total, but ends on line 4)
 			doc = Markly.parse("<!--\nLine 1\nLine 2\n-->")
 			html_node = doc.first_child
 			pos = html_node.source_position
 
 			expect(html_node.type).to be == :html
 			expect(pos[:start_line]).to be == 1
 			# The block starts on line 1 and the closing --> is on line 4
-			expect(pos[:end_line]).to be >= pos[:start_line]
-			expect(pos[:end_line]).to be >= 3  # At least line 3 or more
+			expect(pos[:end_line]).to be == 4
 		end
 
 		it "has correct position for fenced code block" do
@@ -423,6 +421,87 @@
 			expect(pos[:end_line]).to be == 1
 		end
 
+		it "has correct position for multi-line HTML comment (type 2)" do
+			doc = Markly.parse("Para 1\n\n<!--\nContent\n-->\n\nPara 2")
+			
+			html_node = nil
+			doc.each do |node|
+				html_node = node if node.type == :html
+			end
+			
+			expect(html_node).not.to be_nil
+			pos = html_node.source_position
+			expect(pos[:start_line]).to be == 3
+			expect(pos[:end_line]).to be == 5
+		end
+		
+		it "has correct position for multi-line script block (type 1)" do
+			doc = Markly.parse("Para 1\n\n<script>\nalert(1);\n</script>\n\nPara 2")
+			
+			html_node = nil
+			doc.each do |node|
+				html_node = node if node.type == :html
+			end
+			
+			expect(html_node).not.to be_nil
+			pos = html_node.source_position
+			expect(pos[:start_line]).to be == 3
+			expect(pos[:end_line]).to be == 5
+		end
+		
+		it "has correct position for multi-line PHP block (type 3)" do
+			doc = Markly.parse("Para 1\n\n<?php\necho;\n?>\n\nPara 2")
+			
+			html_node = nil
+			doc.each do |node|
+				html_node = node if node.type == :html
+			end
+			
+			expect(html_node).not.to be_nil
+			pos = html_node.source_position
+			expect(pos[:start_line]).to be == 3
+			expect(pos[:end_line]).to be == 5
+		end
+		
+		it "has correct position for multi-line declaration block (type 4)" do
+			doc = Markly.parse("Para 1\n\n<!DOCTYPE\nhtml>\n\nPara 2")
+			
+			html_node = nil
+			doc.each do |node|
+				html_node = node if node.type == :html
+			end
+			
+			expect(html_node).not.to be_nil
+			pos = html_node.source_position
+			expect(pos[:start_line]).to be == 3
+			expect(pos[:end_line]).to be == 4
+		end
+		
+		it "has correct position for multi-line CDATA block (type 5)" do
+			doc = Markly.parse("Para 1\n\n<![CDATA[\ndata\n]]>\n\nPara 2")
+			
+			html_node = nil
+			doc.each do |node|
+				html_node = node if node.type == :html
+			end
+			
+			expect(html_node).not.to be_nil
+			pos = html_node.source_position
+			expect(pos[:start_line]).to be == 3
+			expect(pos[:end_line]).to be == 5
+		end
+		
+		it "has correct position for blank-terminated HTML block (type 6)" do
+			# Types 6-7 end at a blank line, so end_line is the last content line
+			doc = Markly.parse("<div>\ncontent\n</div>\n\nPara 2")
+			html_node = doc.first_child
+			pos = html_node.source_position
+			
+			expect(html_node.type).to be == :html
+			expect(pos[:start_line]).to be == 1
+			expect(pos[:end_line]).to be == 3
+		end
+		
 		it "ensures all nodes have valid position ranges" do
 			# Comprehensive test: no node should have end_line < start_line
 			markdown = <<~MD