fix(cat_controller): use virtual desktop bounds for drag, work area for walk

Split screen boundary usage into two sources:

1. walk / roam / run-to-target (unchanged):
   - self.screen_* = WindowManager.get_work_area() (primary monitor, taskbar-aware)
   - Cat autonomously roams the primary desktop floor only

2. drag clamping (new):
   - self.vd_* = WindowManager.get_virtual_desktop_bounds() (all monitors)
   - on_mouse_move() clamps to vd_left/right/top/bottom instead of
     screen_left/right/top/bottom
   - User can now pick up the cat and drag it to any connected monitor

Previously on_mouse_move() clamped to the primary work area rectangle
(0, 0, 1920, 1032), so moving the cursor past x=1776 would immediately
snap the cat back, making the second monitor unreachable.

catser/cat_controller.py

@@ -83,13 +83,21 @@ class CatController:
         self.config = config
         self.assets = assets
 
-        # Screen boundaries
+        # Primary monitor work area (excludes taskbar) – used for walk/roam floor clamping
         work_area = WindowManager.get_work_area()
-        self.screen_left = work_area[0]
-        self.screen_top = work_area[1]
-        self.screen_right = work_area[2]
+        self.screen_left   = work_area[0]
+        self.screen_top    = work_area[1]
+        self.screen_right  = work_area[2]
         self.screen_bottom = work_area[3]
 
+        # Full virtual desktop spanning ALL monitors – used for drag clamping so
+        # the user can pick up the cat and carry it to a second monitor.
+        vd = WindowManager.get_virtual_desktop_bounds()
+        self.vd_left   = vd[0]
+        self.vd_top    = vd[1]
+        self.vd_right  = vd[2]
+        self.vd_bottom = vd[3]
+
         # Floor position: Cat walks on top of the taskbar / bottom of work area
         self.floor_y = float(self.screen_bottom - self.config.cat_height)
 
@@ -246,9 +254,10 @@ class CatController:
         if self.state == CatState.DRAG:
             new_x = self.drag_start_pos[0] + dx
             new_y = self.drag_start_pos[1] + dy
-            # Keep on screen
-            self.x = max(float(self.screen_left), min(float(self.screen_right - self.config.cat_width), new_x))
-            self.y = max(float(self.screen_top), min(float(self.screen_bottom - self.config.cat_height), new_y))
+            # Clamp to FULL virtual desktop so the cat can be dragged to any monitor.
+            # self.vd_* covers the combined bounds of all connected displays.
+            self.x = max(float(self.vd_left), min(float(self.vd_right  - self.config.cat_width),  new_x))
+            self.y = max(float(self.vd_top),  min(float(self.vd_bottom - self.config.cat_height), new_y))
             self.lift = max(0.0, self.floor_y - self.y)
 
     def on_mouse_up(self, cursor_x: int, cursor_y: int) -> None: