Added multi-paragraph support inside list items and blockquotes.

[heshammahamed]

Problem

A blank line followed by indented continuation inside a list item
broke out of the list entirely, producing a stray <p> instead of
staying inside the <li>:

Input:
* content

  continuation

outputBeforeChanges:
<ul><li>content</li></ul>
<p>continuation</p>

outputAfterChanges:
<ul><li><p>content</p><p>continuation</p></li></ul>

Summary

• Added a new rule to handle multi-paragraph continuation inside list items and blockquotes. When a blank line is followed by indented content, the translator now creates a new <p> inside the current <li> or <blockquote> rather than closing the element.

• Updated ul and ol element tags to wrap <li> content in <p> tag (<ul><li><p> / </p></li></ul>), which is required for multi-paragraph list items to produce valid HTML.

• Update blockquote element tags to wrap content in <p> tag (<blockquote><p> / </p></blockquote>) which is required for multi-paragraph blockquote to produce valid HTML.

Design Decision: Always Loose Lists

The library now always treats lists as loose (content inside <li> is always wrapped in <p>), rather than implementing the CommonMark loose/tight list distinction.

CommonMark definition:

A list is loose if any of its constituent list items are separated by blank lines, or if any of its constituent list items directly contain two block-level elements with a blank line between them. Otherwise a list is tight. The difference in HTML output is that paragraphs in a loose list are wrapped in <p> tags, while paragraphs in a tight list are not.

Implementing this distinction correctly requires look-ahead — the parser must scan the entire list before deciding whether to wrap content in <p>.

Since this library processes Markdown as a left-to-right stream with no look-ahead, implementing true tight/loose detection is not feasible without a significant architectural change.

Treating all lists as loose is a deliberate simplification. The output is valid HTML and is consistent with how many other lightweight Markdown libraries behave.