Fix C# support: wire tree-sitter-c-sharp grammar into parser

C# was listed as a supported language but every .cs file produced
"unsupported language: c-sharp" because the tree-sitter grammar was
never wired up. The comment cited a "module path mismatch", but
github.com/tree-sitter/tree-sitter-c-sharp is a valid Go module path
(hyphens are allowed); the Go package inside simply uses underscores
(tree_sitter_c_sharp), which is standard Go convention.

Fix: add the import and map lang.CSharp to tree_sitter_c_sharp.Language()
in parser.go. Also remove the C# skip from TestAllLanguagesLoad and add
TestParseCSharp to verify class and method parsing.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/modelcontextprotocol/go-sdk v1.3.1
 	github.com/tree-sitter-grammars/tree-sitter-lua v0.4.1
 	github.com/tree-sitter/go-tree-sitter v0.25.0
+	github.com/tree-sitter/tree-sitter-c-sharp v0.23.1
 	github.com/tree-sitter/tree-sitter-cpp v0.23.4
 	github.com/tree-sitter/tree-sitter-go v0.25.0
 	github.com/tree-sitter/tree-sitter-java v0.23.5

go.sum

@@ -40,6 +40,8 @@ github.com/tree-sitter/go-tree-sitter v0.25.0 h1:sx6kcg8raRFCvc9BnXglke6axya12kr
 github.com/tree-sitter/go-tree-sitter v0.25.0/go.mod h1:r77ig7BikoZhHrrsjAnv8RqGti5rtSyvDHPzgTPsUuU=
 github.com/tree-sitter/tree-sitter-c v0.23.4 h1:nBPH3FV07DzAD7p0GfNvXM+Y7pNIoPenQWBpvM++t4c=
 github.com/tree-sitter/tree-sitter-c v0.23.4/go.mod h1:MkI5dOiIpeN94LNjeCp8ljXN/953JCwAby4bClMr6bw=
+github.com/tree-sitter/tree-sitter-c-sharp v0.23.1 h1:ddG6osP34sMieVNN6lu5ZG/3N8Wn+67+43BmipqidyM=
+github.com/tree-sitter/tree-sitter-c-sharp v0.23.1/go.mod h1:H7/aFm5vR1A8Yn5VIOfLWPdlKuJsMgZ5eDmaJdv8bY0=
 github.com/tree-sitter/tree-sitter-cpp v0.23.4 h1:LaWZsiqQKvR65yHgKmnaqA+uz6tlDJTJFCyFIeZU/8w=
 github.com/tree-sitter/tree-sitter-cpp v0.23.4/go.mod h1:doqNW64BriC7WBCQ1klf0KmJpdEvfxyXtoEybnBo6v8=
 github.com/tree-sitter/tree-sitter-embedded-template v0.23.2 h1:nFkkH6Sbe56EXLmZBqHHcamTpmz3TId97I16EnGy4rg=

internal/parser/parser.go

@@ -8,6 +8,7 @@ import (
 
 	tree_sitter_lua "github.com/tree-sitter-grammars/tree-sitter-lua/bindings/go"
 	tree_sitter_cpp "github.com/tree-sitter/tree-sitter-cpp/bindings/go"
+	tree_sitter_c_sharp "github.com/tree-sitter/tree-sitter-c-sharp/bindings/go"
 	tree_sitter_go "github.com/tree-sitter/tree-sitter-go/bindings/go"
 	tree_sitter_java "github.com/tree-sitter/tree-sitter-java/bindings/go"
 	tree_sitter_javascript "github.com/tree-sitter/tree-sitter-javascript/bindings/go"
@@ -35,9 +36,9 @@ func initLanguages() {
 			lang.Go:         tree_sitter.NewLanguage(tree_sitter_go.Language()),
 			lang.Rust:       tree_sitter.NewLanguage(tree_sitter_rust.Language()),
 			lang.Java:       tree_sitter.NewLanguage(tree_sitter_java.Language()),
-			lang.CPP:        tree_sitter.NewLanguage(tree_sitter_cpp.Language()),
-			// C# skipped: upstream module path mismatch (tree-sitter-c-sharp vs tree-sitter-c_sharp)
-			lang.PHP:   tree_sitter.NewLanguage(tree_sitter_php.LanguagePHPOnly()),
+			lang.CPP:    tree_sitter.NewLanguage(tree_sitter_cpp.Language()),
+			lang.CSharp: tree_sitter.NewLanguage(tree_sitter_c_sharp.Language()),
+			lang.PHP:    tree_sitter.NewLanguage(tree_sitter_php.LanguagePHPOnly()),
 			lang.Lua:   tree_sitter.NewLanguage(tree_sitter_lua.Language()),
 			lang.Scala: tree_sitter.NewLanguage(tree_sitter_scala.Language()),
 		}

internal/parser/parser_test.go

@@ -77,9 +77,6 @@ class MyClass:
 
 func TestAllLanguagesLoad(t *testing.T) {
 	for _, l := range lang.AllLanguages() {
-		if l == lang.CSharp {
-			continue // C# grammar has broken Go module path upstream
-		}
 		_, err := GetLanguage(l)
 		if err != nil {
 			t.Errorf("GetLanguage(%s): %v", l, err)
@@ -87,6 +84,50 @@ func TestAllLanguagesLoad(t *testing.T) {
 	}
 }
 
+func TestParseCSharp(t *testing.T) {
+	source := []byte(`using System;
+
+namespace MyApp {
+    public class Greeter {
+        public string Greet(string name) {
+            return $"Hello, {name}";
+        }
+
+        private void Helper() {}
+    }
+
+    public enum Color { Red, Green, Blue }
+}
+`)
+	tree, err := Parse(lang.CSharp, source)
+	if err != nil {
+		t.Fatalf("Parse C#: %v", err)
+	}
+	defer tree.Close()
+
+	root := tree.RootNode()
+	if root == nil {
+		t.Fatal("root node is nil")
+	}
+
+	var classCount, methodCount int
+	Walk(root, func(n *tree_sitter.Node) bool {
+		switch n.Kind() {
+		case "class_declaration":
+			classCount++
+		case "method_declaration":
+			methodCount++
+		}
+		return true
+	})
+	if classCount != 1 {
+		t.Errorf("expected 1 class_declaration, got %d", classCount)
+	}
+	if methodCount != 2 {
+		t.Errorf("expected 2 method_declarations, got %d", methodCount)
+	}
+}
+
 func TestNodeText(t *testing.T) {
 	source := []byte(`package main