refactor(strip_html): unify raw-text blocks; treat <!--...--> as opaque

In HTML5, <script>, <style>, and <!-- --> are all raw-text blocks: their
content is opaque until the matching closer, so a `>` inside CSS, JS, or
a comment must not be treated as a tag end. The previous code only had
this special handling for <script> and <style>; comments containing `>`
fell through to the generic `<...>` branch and were partially stripped
(e.g. `<!-- a > b -->` left `b -->` in the output).

Match Shopify Liquid's STRIP_HTML_BLOCKS set (script + style + comment),
and consolidate the three near-identical branches into a small
opener/closer table inside the function.

Algorithm and complexity unchanged (O(n) via indexOf + cached closer
positions). Add a regression test for `>` inside a comment.

Co-authored-by: Cursor <[email protected]>

test/integration/filters/html.spec.ts

@@ -57,6 +57,9 @@ describe('filters/html', function () {
     it('should strip multiline comments', function () {
       expect(liquid.parseAndRenderSync('{{"<!--foo\r\nbar \ncoo\t  \r\n  -->"|strip_html}}')).toBe('')
     })
+    it('should treat > inside comments as comment content (not a tag end)', function () {
+      expect(liquid.parseAndRenderSync('{{ "<!-- a > b -->after" | strip_html }}')).toBe('after')
+    })
     it('should strip all style tags and their contents', function () {
       return test('{{ "<style>cite { font-style: italic; }</style><cite>Ulysses<cite>?" | strip_html }}',
         'Ulysses?')