HDR: honest wording (not native/per-game HDR)

Rename "native HDR" to "HDR output (scRGB inverse tone mapping)" in the
settings tooltip and code comments. The feature expands the final SDR
image into an scRGB float swapchain and inverse-tone-maps it (lift
highlights, keep blacks) — an AutoHDR-style retrofit, not native
per-game HDR. The toggle behaviour is unchanged.

src/Ryujinx.Graphics.OpenGL/Window.cs

@@ -426,7 +426,7 @@ namespace Ryujinx.Graphics.OpenGL
 
         public void SetHdrMode(bool enabled, float paperWhite, float peak, float curve)
         {
-            // Native HDR output is only implemented on the Vulkan backend.
+            // HDR output (scRGB inverse tone mapping) is only implemented on the Vulkan backend.
         }
     }
 }

src/Ryujinx.Graphics.Vulkan/Window.cs

@@ -232,7 +232,7 @@ namespace Ryujinx.Graphics.Vulkan
 
         private static SurfaceFormatKHR ChooseSwapSurfaceFormat(SurfaceFormatKHR[] availableFormats, bool colorSpacePassthroughEnabled, bool hdrEnabled)
         {
-            // Native HDR output: when HDR is enabled and the surface advertises the scRGB
+            // HDR output (scRGB inverse tone mapping): when HDR is enabled and the surface advertises the scRGB
             // (extended sRGB linear) HDR colorspace, select the 16-bit float swapchain. That
             // colorspace is only enumerated on a genuinely HDR-capable display/OS, so on an SDR
             // display this branch never triggers and the normal SDR format is used unchanged.

src/Ryujinx/Systems/Configuration/ConfigurationFileFormat.cs

@@ -70,7 +70,7 @@ namespace Ryujinx.Ava.Systems.Configuration
         public int ScalingFilterLevel { get; set; }
 
         /// <summary>
-        /// Enables or disables native HDR output (scRGB) with SDR->HDR tone mapping.
+        /// Enables or disables HDR output (scRGB) via SDR->HDR inverse tone mapping (AutoHDR-style retrofit, not native per-game HDR).
         /// </summary>
         public bool EnableHdr { get; set; }
 

src/Ryujinx/Systems/Configuration/ConfigurationState.Model.cs

@@ -621,7 +621,7 @@ namespace Ryujinx.Ava.Systems.Configuration
             public ReactiveObject<int> ScalingFilterLevel { get; private set; }
 
             /// <summary>
-            /// Enables or disables native HDR output (scRGB) with SDR->HDR tone mapping.
+            /// Enables or disables HDR output (scRGB) via SDR->HDR inverse tone mapping (AutoHDR-style retrofit, not native per-game HDR).
             /// </summary>
             public ReactiveObject<bool> EnableHdr { get; private set; }
 

src/Ryujinx/UI/Views/Settings/SettingsGraphicsView.axaml

@@ -96,7 +96,7 @@
                             <TextBlock Text="{ext:Locale SettingsEnableColorSpacePassthrough}" />
                         </CheckBox>
                         <CheckBox IsChecked="{Binding EnableHdr}"
-                            ToolTip.Tip="Outputs native HDR (scRGB) with SDR-&gt;HDR tone mapping. Only engages on an HDR-capable display with HDR enabled in the OS; SDR displays are unaffected. Vulkan only.">
+                            ToolTip.Tip="Expands the SDR image to HDR via inverse tone mapping into an scRGB float swapchain — similar to Windows AutoHDR, but tuned to keep blacks black and only lift highlights. This is not native/per-game HDR: the game still renders in SDR. Only engages on an HDR-capable display with HDR enabled in the OS; SDR displays are unaffected. Vulkan only.">
                             <TextBlock Text="Enable HDR (experimental)" />
                         </CheckBox>
                         <StackPanel Orientation="Horizontal" Margin="24,4,0,0" IsVisible="{Binding EnableHdr}">