fix: enable HTML tag folding (#97)

[hybridmachine]

Summary

• Enable HTML tag folding by setting fold.html=1 for hypertext, phpscript, and xml lexers in applyLanguageToView()
• Add fold.hypertext.comment=1 for embedded script comment folding (Windows parity)
• Set lexer.xml.allow.scripts=0 for XML files to match upstream setXmlLexer() behavior

Closes #97

Test plan

• Open an HTML file — verify fold markers appear next to tag pairs (<div>, <section>, etc.)
• Click a fold marker — content between open/close tags should collapse
• Verify nested tags create nested, independently foldable regions
• Verify self-closing tags (<br/>, <img/>) do NOT create fold points
• Open an XML file — verify tag folding works
• Open a PHP file — verify tag folding works
• Open a C++ file — verify brace folding still works (no regression)
• Open a Python file — verify indent folding still works (no regression)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Enables HTML/XML tag folding support in the macOS Scintilla integration by setting LexHTML-related folding (and XML script-handling) properties during language application.

Changes:

• Set fold.html=1 for hypertext, phpscript, and xml lexers to enable tag folding.
• Enable embedded-script comment folding via fold.hypertext.comment=1 (Windows parity).
• Disable embedded scripts for XML via lexer.xml.allow.scripts=0 to match upstream behavior.

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[Copilot]

lexer.xml.allow.scripts is only set to "0" for the XML lexer, but never reset when switching to other LexHTML-based lexers (e.g., "hypertext"). In LexHTML.cxx this flag controls whether <script> tags enter a script state at all, so opening an XML file first could disable script lexing (and related folding) in subsequent HTML/PHP views. Consider explicitly setting this property to "1" for non-XML lexers (or at least for "hypertext"/"phpscript") inside applyLanguageToView() so language switches don’t inherit the XML-only setting.

Suggested change

	// HTML-family fold properties (hypertext, phpscript, xml all use LexHTML.cxx)
	if (strcmp(lang.lexerName, "hypertext") == 0 ||
	strcmp(lang.lexerName, "phpscript") == 0 ||
	strcmp(lang.lexerName, "xml") == 0)
	{
	ScintillaBridge_sendMessage(sci, SCI_SETPROPERTY, (uintptr_t)"fold.html", (intptr_t)"1");
	ScintillaBridge_sendMessage(sci, SCI_SETPROPERTY, (uintptr_t)"fold.hypertext.comment", (intptr_t)"1");
	}
	// XML: disable embedded scripts (matches upstream setXmlLexer behavior)
	if (strcmp(lang.lexerName, "xml") == 0)
	{
	ScintillaBridge_sendMessage(sci, SCI_SETPROPERTY, (uintptr_t)"lexer.xml.allow.scripts", (intptr_t)"0");
	// HTML-family properties (hypertext, phpscript, xml all use LexHTML.cxx)
	if (strcmp(lang.lexerName, "hypertext") == 0 ||
	strcmp(lang.lexerName, "phpscript") == 0 ||
	strcmp(lang.lexerName, "xml") == 0)
	{
	ScintillaBridge_sendMessage(sci, SCI_SETPROPERTY, (uintptr_t)"fold.html", (intptr_t)"1");
	ScintillaBridge_sendMessage(sci, SCI_SETPROPERTY, (uintptr_t)"fold.hypertext.comment", (intptr_t)"1");
	// XML disables embedded scripts; other LexHTML-based lexers must re-enable them
	// so switching away from XML does not inherit the XML-only setting.
	ScintillaBridge_sendMessage(
	sci,
	SCI_SETPROPERTY,
	(uintptr_t)"lexer.xml.allow.scripts",
	(intptr_t)(strcmp(lang.lexerName, "xml") == 0 ? "0" : "1"));