docs: update STATUS.md and DEFERRED.md with docking system

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/DEFERRED.md

@@ -151,7 +151,7 @@
 - **에셋 브라우저** — 파일 시스템 탐색 미구현.
 - ~~**텍스트 입력**~~ ✅ text_input 위젯 완료.
 - ~~**스크롤, 드래그앤드롭**~~ ✅ scroll_panel + drag/drop 완료.
-- **도킹, 탭, 윈도우 드래그** — 미구현.
+- ~~**도킹, 탭**~~ ✅ DockTree (이진 분할, 리사이즈, 탭 전환) 완료. **플로팅 윈도우/탭 드래그 이동** 미구현.
 - **TTF 폰트** — 비트맵 고정폭만.
 
 ## 렌더링 한계

docs/STATUS.md

@@ -121,6 +121,7 @@
 - voltex_editor: DrawList, UiContext, UiRenderer
 - voltex_editor: Widgets (text, button, slider, checkbox, panel, text_input, scroll_panel)
 - voltex_editor: Drag and Drop (begin_drag, drop_target)
+- voltex_editor: DockTree (binary split layout, resize, tab switching)
 - examples/editor_demo
 
 ## Crate 구조
@@ -137,10 +138,10 @@ crates/
 ├── voltex_ai        — NavMesh(+builder), A*, Funnel, steering, obstacle avoidance
 ├── voltex_net       — UDP, NetServer/Client, Reliable/Ordered, Snapshot(delta), Interpolation
 ├── voltex_script    — Lua 5.4, LuaState, table interop, coroutine, sandbox, hot reload
-└── voltex_editor    — IMGUI, text_input, scroll, drag&drop, UiRenderer
+└── voltex_editor    — IMGUI, text_input, scroll, drag&drop, docking, UiRenderer
 ```
 
-## 테스트: 485개 전부 통과
+## 테스트: 501개 전부 통과
 
 - voltex_math: 37
 - voltex_platform: 3
@@ -152,7 +153,7 @@ crates/
 - voltex_ai: 24
 - voltex_net: 36
 - voltex_script: 18
-- voltex_editor: 22
+- voltex_editor: 38
 
 ## Examples (12개 + survivor_game)