Update C# grammar

[wherewhere]

• Primary constructors f28b268
• field keyword in properties (I don't know how to make it only exist in properties) 8e6706d
• allows ref struct constraint 7837d7a
• Extensions f944628
• Raw string literals (I don't know how to do it)
• Collection Expressions (Conflict with InitializerTarget)

[macroscopeapp]

Expand C# grammar to support extension blocks, updated generic constraints including 'allows' and nullable markers, additional preprocessor directives, 'field' expressions, and string 'U8'/'u8' suffixes in syntax.grammar

This pull request updates the C# grammar and development tooling. It adds new language constructs and constraints to the grammar, introduces extension blocks with members, and updates build/watch dependencies and configuration. Non-functional changes include formatting updates to development files and tokenizers.

• Add extension block declarations with member support and constraints in syntax.grammar
• Expand generic constraint parsing to include allows clauses, ref struct, optional ? on class/struct, default constraints, and comma-separated constraints in syntax.grammar
• Add new preprocessor directives load, nullable, reference (r), and custom identifiers in syntax.grammar
• Add field expressions and include them in primary expressions; allow U8/u8 suffix on regular and verbatim strings in syntax.grammar
• Update class/struct/interface/enum declarations to support parameter lists before base clauses and optional semicolon-only forms; allow constructor-like arguments for first base type in syntax.grammar
• Configure the dev CodeMirror editor to use a four-space indentation unit in index.ts
• Switch the dev watch script to @marijn/buildtool and pass buildhelper options in watch.cjs; update related dependencies in package.json
• Apply formatting-only changes to index.html, print-lezer-tree.ts, and tokenizer files in tokens.ts

📍Where to Start

Start with the grammar changes in syntax.grammar, focusing on extensionBlockDecl, typeParamConstraintsClause, preprocessor directive rules, and updated declaration forms.

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Macroscope summarized 24e00f4.

[PaperPrototype]

Syntax highlighting breaks down when using top level statements

repro using codemirror-lang-csharp@6.2.0: https://www.sharptoy.net/
top level statements in C#: https://learn.microsoft.com/en-us/dotnet/csharp/fundamentals/program-structure/top-level-statements

[wherewhere]

I try to add it, but it broke more...
3aec1cc

[wherewhere]

I try to add it, but it broke more...
3aec1cc

[PaperPrototype]

Oof, hmm, maybe the grammer architecture needs a more complex ruleset. I wonder if claude code could take a crack at it...