fix(dock): restore TYPE_CHECKING guards to break circular imports

animator.py and layout.py both circular-import from canvas.py.
Restore the TYPE_CHECKING blocks and suppress TC004 globally.

src/window/dock/animator.py

@@ -1,11 +1,13 @@
-from typing import Optional
+from typing import TYPE_CHECKING, Optional
 
 from fabric.utils import GLib
 
-from .canvas import DockCanvas
 from .constants import ANIM_INTERVAL_MS, IDLE_THRESHOLD, LERP_FACTOR
 from .layout import DockLayout
 
+if TYPE_CHECKING:
+    from .canvas import DockCanvas
+
 
 class DockAnimator:
     def __init__(self, canvas: DockCanvas):

src/window/dock/layout.py

@@ -1,7 +1,6 @@
 import math
-from typing import List, Tuple
+from typing import TYPE_CHECKING, List, Tuple
 
-from .canvas import DockItem
 from .constants import (
     BG_PADDING_H,
     BG_PADDING_V,
@@ -12,6 +11,9 @@ from .constants import (
     SIGMA_FACTOR,
 )
 
+if TYPE_CHECKING:
+    from .canvas import DockItem
+
 
 class DockLayout:
     @staticmethod