fix(resolution): a call through a declared member calls that member's type (#2171)

C# / Java / Kotlin receivers that are fields, properties or parameters were
typed only when declared in the calling method without generics, so a call
through a field fell to the receiver-word guess: Newtonsoft's
_innerWriter.WriteValue() landed on the wrapper's own WriteValue, a
TextWriter's Write() on a test writer's, commons-lang's DateFormat field's
parse() on DateParser 284 times.

- read class-level member declarations (brace depth 1, comments skipped),
  walking base classes with their type arguments substituted, C# using
  aliases, type-parameter bounds, generic and for-each declarations
- C# interface members default public and namespace-level types internal
  (TS extractor + kernel, parity 0 diffs); interface calls resolve at all
- the receiver-word guess weighs the owner type's name only, the receiver's
  last link (a constant's type), and its head noun; .NET std names need a
  receiver named after the owner; production code never lands in a test
  suite's mock

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

codegraph-kernel/src/csharp.rs

@@ -418,7 +418,8 @@ impl<'t> Walker<'t> {
     // Java-style `modifiers` wrapper (probed).
 
     /// getVisibility: FIRST `modifier` child whose text is one of the four
-    /// levels wins; none → private (the C# default).
+    /// levels wins; none → public in an interface, internal in a namespace
+    /// or the file, private in a class or struct (the C# defaults).
     fn visibility_of(&self, node: Node) -> u8 {
         for i in 0..node.child_count() {
             let Some(child) = node.child(i) else { continue };
@@ -432,7 +433,17 @@ impl<'t> Walker<'t> {
                 }
             }
         }
-        2 // C# defaults to private
+        let parent = node.parent();
+        let container = match parent {
+            Some(p) if p.kind() == "declaration_list" => p.parent(),
+            other => other,
+        };
+        match container.map(|c| c.kind()) {
+            Some("interface_declaration") => 1,
+            None | Some("compilation_unit") | Some("namespace_declaration")
+            | Some("file_scoped_namespace_declaration") => 4,
+            _ => 2,
+        }
     }
 
     fn is_static(&self, node: Node) -> bool {