Make the eyedropper a hybrid material/screen pick

On a foreign object the pipette now reads the data channels
(metallic/smoothness/occlusion/emission) texel-exact from the material
while taking albedo from the rendered, fully-lit on-screen pixel - so the
picked colour honours baked lightmaps/ambient/SSAO while keeping the
material's PBR fidelity. Falls back to a pure screen pick when no readable
UV is available. Pull the render+readback out of PickFromScreen into a
shared TrySampleScreenColor.

The pipette now also arms on Ctrl (in addition to Shift), and Ctrl+wheel
resizes the brush; the orbit camera ignores the wheel while either modifier
is held so it does not zoom and resize at once.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scripts/ThirdPersonOrbitInput.cs

@@ -191,9 +191,9 @@ public class ThirdPersonOrbitInput : MonoBehaviour
 
             float scale = CurrentScale();
 
-            // Shift+wheel is reserved for the paint brush resize (MeshPainter), so the orbit camera
-            // ignores the wheel while Shift is held - otherwise it would zoom and resize at once.
-            float scroll = ShiftHeld() ? 0f : ReadScroll();
+            // Shift/Ctrl+wheel is reserved for the paint brush resize (MeshPainter), so the orbit camera
+            // ignores the wheel while either is held - otherwise it would zoom and resize at once.
+            float scroll = (ShiftHeld() || CtrlHeld()) ? 0f : ReadScroll();
             if (!Mathf.Approximately(scroll, 0f))
             {
                 // One wheel notch = one zoom step (sign only), independent of the platform's raw wheel
@@ -280,6 +280,19 @@ public class ThirdPersonOrbitInput : MonoBehaviour
 #endif
     }
 
+    static bool CtrlHeld()
+    {
+#if ENABLE_INPUT_SYSTEM
+        var kb = Keyboard.current;
+        if (kb != null) return kb.leftCtrlKey.isPressed || kb.rightCtrlKey.isPressed;
+#endif
+#if ENABLE_LEGACY_INPUT_MANAGER
+        return Input.GetKey(KeyCode.LeftControl) || Input.GetKey(KeyCode.RightControl);
+#else
+        return false;
+#endif
+    }
+
     Vector2 ReadMouseDelta()
     {
 #if ENABLE_INPUT_SYSTEM