feat(extract): build containment tree and traverse all containers

Add buildTree to mirror how TTS nests objects, with a display label
(Nickname or class Name). Generalize traverseMod to descend into any
object with ContainedObjects, not just bags, and add Nickname to
TTSObject.

packages/extract/src/traverse.test.ts

@@ -43,9 +43,9 @@ describe('markParent', () => {
 });
 
 describe('traverseMod', () => {
-  it('yields every non-bag object in order', () => {
+  it('yields every object including containers, in order', () => {
     const guids = [...traverseMod(mod)].map((o) => o.GUID);
-    expect(guids).toEqual(['a', 'c', 'e', 'f']);
+    expect(guids).toEqual(['a', 'b', 'c', 'd', 'e', 'f']);
   });
 
   it('descends into nested bags', () => {
@@ -53,8 +53,14 @@ describe('traverseMod', () => {
     expect(guids).toContain('e');
   });
 
+  it('descends into any object with ContainedObjects', () => {
+    const custom = { Name: 'Custom_Model', GUID: 'x', Description: '', ContainedObjects: [card('y')] };
+    const guids = [...traverseMod(custom)].map((o) => o.GUID);
+    expect(guids).toEqual(['x', 'y']);
+  });
+
   it('accepts a single object', () => {
     const guids = [...traverseMod(bag('b', [card('c')]))].map((o) => o.GUID);
-    expect(guids).toEqual(['c']);
+    expect(guids).toEqual(['b', 'c']);
   });
 });