feat: Add Rust trait inheritance and impl block extraction with method receiver type support

Addresses Rust's impl block syntax where trait implementations (`impl Trait for Type`) and trait supertraits (`trait Sub: Super`) create inheritance relationships. Adds getReceiverType to extract method receiver types from impl blocks, enabling proper method-to-struct relationships and qualified name resolution. Verified against Deno codebase and moved from "Needs Verification" to completed language support.

__tests__/extraction.test.ts

@@ -650,6 +650,78 @@ pub trait Repository {
     expect(traitNode).toBeDefined();
     expect(traitNode?.name).toBe('Repository');
   });
+
+  it('should extract impl Trait for Type as implements edges', () => {
+    const code = `
+pub struct MyCache {}
+
+pub trait Cache {
+    fn get(&self, key: &str) -> Option<String>;
+}
+
+impl Cache for MyCache {
+    fn get(&self, key: &str) -> Option<String> {
+        None
+    }
+}
+`;
+    const result = extractFromSource('cache.rs', code);
+
+    // Should have an unresolved reference for implements
+    const implRef = result.unresolvedReferences.find(
+      (r) => r.referenceKind === 'implements' && r.referenceName === 'Cache'
+    );
+    expect(implRef).toBeDefined();
+
+    // The struct MyCache should be the source
+    const myCacheNode = result.nodes.find((n) => n.name === 'MyCache' && n.kind === 'struct');
+    expect(myCacheNode).toBeDefined();
+    expect(implRef?.fromNodeId).toBe(myCacheNode?.id);
+  });
+
+  it('should extract trait supertraits as extends references', () => {
+    const code = `
+pub trait Display {}
+
+pub trait Error: Display {
+    fn description(&self) -> &str;
+}
+`;
+    const result = extractFromSource('error.rs', code);
+
+    const extendsRef = result.unresolvedReferences.find(
+      (r) => r.referenceKind === 'extends' && r.referenceName === 'Display'
+    );
+    expect(extendsRef).toBeDefined();
+
+    const errorTrait = result.nodes.find((n) => n.name === 'Error' && n.kind === 'trait');
+    expect(errorTrait).toBeDefined();
+    expect(extendsRef?.fromNodeId).toBe(errorTrait?.id);
+  });
+
+  it('should not create implements edges for plain impl blocks', () => {
+    const code = `
+pub struct Counter {
+    count: u32,
+}
+
+impl Counter {
+    pub fn new() -> Counter {
+        Counter { count: 0 }
+    }
+    pub fn increment(&mut self) {
+        self.count += 1;
+    }
+}
+`;
+    const result = extractFromSource('counter.rs', code);
+
+    // Should have no implements references (no trait involved)
+    const implRefs = result.unresolvedReferences.filter(
+      (r) => r.referenceKind === 'implements'
+    );
+    expect(implRefs).toHaveLength(0);
+  });
 });
 
 describe('Java Extraction', () => {