feat: add basic markdown syntax test files

Add comprehensive test suite for basic markdown syntax features:
- basic-headings.md: All heading levels and setext syntax
- basic-paragraphs-line-breaks.md: Paragraph separation and line breaks
- basic-emphasis.md: Bold and italic formatting
- basic-blockquotes.md: Blockquotes with nested content
- basic-lists.md: Ordered and unordered lists with nesting
- basic-code.md: Inline code and code blocks
- basic-horizontal-rules.md: Horizontal rule variants
- basic-links-and-images.md: Links and images with various syntax
- basic-escaping.md: Character escaping
- basic-index.md: Index of all test files

All files follow the Markdown Guide's Basic Syntax specification.

test/markdown/basic-code.md

@@ -0,0 +1,306 @@
+# Basic Code Test
+
+This file tests inline code and code block syntax in markdown.
+
+## Inline Code
+
+Inline code is created using backticks (`` ` ``) around the text.
+
+This paragraph contains `inline code`.
+
+You can use `inline code` anywhere in a sentence.
+
+`Code` can appear at the start of a sentence.
+
+A sentence can end with `code`.
+
+## Code Blocks
+
+Code blocks are created using triple backticks (``` ``` ```) on lines before and after the code.
+
+```
+This is a code block.
+It can contain multiple lines.
+Each line is preserved as written.
+```
+
+## Code Blocks with Language
+
+Code blocks can specify a programming language for syntax highlighting.
+
+```javascript
+function example() {
+  return "Hello, World!";
+}
+```
+
+```python
+def example():
+    return "Hello, World!"
+```
+
+```html
+<div>
+  <p>Hello, World!</p>
+</div>
+```
+
+```css
+.example {
+  color: blue;
+  font-size: 16px;
+}
+```
+
+## Multiple Code Blocks
+
+Multiple code blocks can appear consecutively.
+
+```
+First code block
+```
+
+```
+Second code block
+```
+
+```
+Third code block
+```
+
+## Code Blocks with Formatting
+
+Code blocks preserve all formatting, including spaces and indentation.
+
+```
+    This code block
+        has indentation
+            that should be preserved
+```
+
+```
+function example() {
+    if (condition) {
+        return value;
+    }
+}
+```
+
+## Code Blocks with Special Characters
+
+Code blocks can contain special characters and symbols.
+
+```
+!@#$%^&*()
+[]{}()
+<>
+```
+
+```
+function test() {
+  console.log("Hello, World!");
+  return 123;
+}
+```
+
+## Inline Code with Special Characters
+
+Inline code can contain special characters.
+
+This has `code with !@#$%` in it.
+
+This has `code with ()[]{}` in it.
+
+This has `code with <>&` in it.
+
+## Escaping Backticks in Inline Code
+
+To include a backtick in inline code, use double backticks.
+
+This contains `` `backtick` `` in the code.
+
+This contains `` `code with backticks` `` in it.
+
+## Code Blocks with Empty Lines
+
+Code blocks can contain empty lines.
+
+```
+First line
+
+Third line
+```
+
+```
+Line one
+
+Line three
+
+Line five
+```
+
+## Code Blocks with Only Whitespace
+
+Code blocks can contain only whitespace.
+
+```
+    
+```
+
+```
+    
+
+```
+
+## Inline Code in Different Contexts
+
+Inline code can appear in various contexts.
+
+### In Paragraphs
+
+This paragraph has `inline code` in it.
+
+### In Lists
+
+- Item with `inline code`
+- Another item with `code`
+
+1. Ordered item with `inline code`
+2. Another ordered item with `code`
+
+### In Blockquotes
+
+> This blockquote contains `inline code`.
+
+### In Headings
+
+### Heading with `Code`
+
+## Code Blocks in Different Contexts
+
+### Code Blocks After Paragraphs
+
+This is a paragraph.
+
+```
+Code block after paragraph
+```
+
+### Code Blocks Before Paragraphs
+
+```
+Code block before paragraph
+```
+
+This is a paragraph.
+
+### Code Blocks Between Paragraphs
+
+This is the first paragraph.
+
+```
+Code block in the middle
+```
+
+This is the second paragraph.
+
+### Code Blocks in Lists
+
+- List item before code block
+
+  ```
+  Code block in list
+  ```
+
+- List item after code block
+
+### Code Blocks in Blockquotes
+
+> This is a blockquote with a code block:
+>
+> ```
+> Code block in blockquote
+> ```
+
+## Long Code Blocks
+
+Code blocks can contain very long lines of code.
+
+```
+This is a very long line of code that extends far beyond the normal width and should demonstrate how code blocks handle extended content that might require horizontal scrolling or wrapping depending on the rendering implementation.
+```
+
+```
+function veryLongFunctionNameThatExtendsBeyondNormalWidth(parameterOne, parameterTwo, parameterThree, parameterFour) {
+  return parameterOne + parameterTwo + parameterThree + parameterFour;
+}
+```
+
+## Code Blocks with Many Lines
+
+Code blocks can contain many lines of code.
+
+```javascript
+function example() {
+  let x = 1;
+  let y = 2;
+  let z = 3;
+  let a = 4;
+  let b = 5;
+  let c = 6;
+  let d = 7;
+  let e = 8;
+  let f = 9;
+  let g = 10;
+  return x + y + z + a + b + c + d + e + f + g;
+}
+```
+
+## Edge Cases
+
+### Inline Code with Only Spaces
+
+`    `
+
+### Inline Code with Only Special Characters
+
+`!@#$%^&*()`
+
+### Very Short Inline Code
+
+`` `a` ``
+
+### Inline Code at Word Boundaries
+
+`code`word
+
+word`code`
+
+### Code Block with Only One Line
+
+```
+Single line code block
+```
+
+### Code Block with Trailing Spaces
+
+```
+Code block with trailing spaces    
+```
+
+### Unclosed Code Block
+
+```
+This code block is not closed properly
+
+### Code Block with Language but No Code
+
+```javascript
+```
+
+### Inline Code with Backticks
+
+`` `code` ``
+
+`` ``code`` ``
+