FIX: Enforce a minimum window size on the Input Debugger window [UUM-137119]

The Input Debugger window never assigned a minimum size, so it could be resized arbitrarily small until its toolbar and device/action/layout tree view were no longer usably visible.

InputDebuggerWindow.OnEnable() previously set only titleContent; it now also assigns minSize = new Vector2(270, 300), mirroring the sibling InputDeviceDebuggerWindow. Setting the minimum in OnEnable rather than CreateOrShow() re-applies it after domain reloads and when a persisted or docked window is restored from the editor layout, not only when the window is first opened from the menu.

Jira: https://jira.unity3d.com/browse/UUM-137119

Author: Pauliusd01

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Fixed
 
+- Fixed the Input Debugger window (Window > Analysis > Input Debugger) being resizable arbitrarily small until its toolbar and device/action/layout tree view were no longer usably visible; it now enforces a minimum window size [UUM-137119](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-137119)
 - Fixed the Action Maps list in the Input Actions editor losing keyboard focus after deleting a map, so that Delete, Duplicate, and arrow-key navigation kept working on the auto-selected replacement map without requiring an extra click [UUM-147152](https://issuetracker.unity3d.com/product/unity/issues/guid/UUM-147152)
 
 ## [1.20.0] - 2026-07-21

Packages/com.unity.inputsystem/InputSystem/Editor/Debugger/InputDebuggerWindow.cs

@@ -84,6 +84,7 @@ public static void Disable()
         private void OnEnable()
         {
             titleContent = new GUIContent("Input Debugger");
+            minSize = new Vector2(270, 300);
         }
 
         private void OnDeviceChange(InputDevice device, InputDeviceChange change)