Persist material scalars, reset the HUD, and split alpha from the picker

Save and restore the emission intensity and the three camo knobs
(half-Lambert, half-Lambert brightness, specular dampen) with a named
painting. The .paint format moves to v3 with a small scalar block
between the header and the pixel maps; v2 paintings still load with
their painter values left untouched. Loading re-syncs the emission and
camo sliders, and peers pick the values up for free through the
existing owner-authoritative paint NetworkVariables.

Add a HUD reset (Lib_ResetHud button plus context-menu fallback) that
behaves as if the saved hud-layout file were deleted: it removes the
file, restores panels to their authored prefab positions, and resets
the brush values to the painter/material defaults captured before any
carry/restore runs.

Remove the alpha bar from HsvColorPicker so alpha is driven by
standalone Slider_AlbedoAlpha / Slider_EmissionAlpha bindings; the
picker now writes RGB only and the sliders write alpha only, with no
feedback between them. Add a generic SliderCurve component that reshapes
a slider's handle position into a non-linear value (with an inverse for
setting values back), and make the slider wiring curve-aware.

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

Assets/Scripts/PaintHud.Library.cs

@@ -21,6 +21,7 @@ public partial class PaintHud
     private const string LibSaveButton = "Lib_Save";
     private const string LibLoadButton = "Lib_Load";
     private const string LibDeleteButton = "Lib_Delete";
+    private const string LibResetButton = "Lib_ResetHud";
     private const string LibSaveDialog = "Lib_SaveDialog";
     private const string LibNameInput = "Lib_NameInput";
     private const string LibSaveInfo = "Lib_SaveInfo";
@@ -34,7 +35,7 @@ public partial class PaintHud
     private bool _libraryBound;
     private RectTransform _listContent;
     private GameObject _entryTemplate;
-    private Button _saveButton, _loadButton, _deleteButton;
+    private Button _saveButton, _loadButton, _deleteButton, _resetButton;
     private string _selectedPainting;
 
     // Save dialog
@@ -76,9 +77,11 @@ public partial class PaintHud
         _saveButton = Find<Button>(root, LibSaveButton);
         _loadButton = Find<Button>(root, LibLoadButton);
         _deleteButton = Find<Button>(root, LibDeleteButton);
+        _resetButton = Find<Button>(root, LibResetButton); // optional: present only if authored in the layout
         Hook(_saveButton, OnSaveClicked);
         Hook(_loadButton, OnLoadClicked);
         Hook(_deleteButton, OnDeleteClicked);
+        Hook(_resetButton, OnResetClicked);
 
         var sd = FindDeep(root, LibSaveDialog);
         _saveDialog = sd ? sd.gameObject : null;
@@ -233,11 +236,27 @@ public partial class PaintHud
         ShowConfirm($"Delete \"{name}\"?", OkDanger, () => DoDelete(name));
     }
 
+    /// <summary>Reset the panels + brush values to their authored defaults (confirmed; the dialog reuses the
+    /// library's confirm path). Falls back to an immediate reset if no confirm dialog is authored.</summary>
+    private void OnResetClicked()
+    {
+        if (_confirmDialog)
+            ShowConfirm("Reset the HUD panels and brush values to their defaults?", OkDanger, ResetHudToDefaults);
+        else
+            ResetHudToDefaults();
+    }
+
     private void DoLoad(string name)
     {
         if (!painter || !painter.LoadPaintByName(name)) return;
 
-        // Re-sync the loaded baseline to every other peer (no-op offline / single-player).
+        // The load also restored the slot's emission intensity + camo knobs onto the painter (v3 slots) ->
+        // push them into the sliders so the HUD reflects the loaded look, exactly like a pipette pick does.
+        SyncFromPainter();
+        SyncCamoSliders();
+
+        // Re-sync the loaded baseline to every other peer (no-op offline / single-player). The restored
+        // emission/camo replicate on their own via PlayerPaintSync's owner-authoritative NetworkVariables.
         var sync = painter.GetComponentInParent<PlayerPaintSync>();
         if (sync) sync.BroadcastLoadedPaint();
     }