Phase 7: cockpit overlay generator, region extraction, and profile editor

Overlay generator (pure, tested) — RioJoy.Core/Overlay:
- FontFitter ports the legacy calc-fontsize auto-fit search (validated against a
  brute-force oracle); OverlayLayoutEngine ports create-data-layer's fit + h/v
  justification and adds per-region 90 deg CCW rotation; OverlayTemplate/Region +
  OverlayTemplateStore hold cell geometry/colour/rotation (regions.json).
- GoobieDataImporter parses the legacy .data label sheet into label rows.
- src/RioJoy.Overlay: SkiaSharp rasterizer (SkiaTextMeasurer shared with the engine
  so measured layout == drawn output; SkiaOverlayRenderer -> PNG;
  ProfileWallpaperGenerator). Verified end-to-end on the real cockpit art
  (regions.json + riojoy.png + TEST.data) by OverlayRenderIntegrationTests.
- RioJoy.Tray/WallpaperApplier applies via SystemParametersInfo; RioCoordinator
  generates+applies on profile activation (opt-in via AppConfig.OverlayTemplatePath).

Region geometry — tools/XcfRegionExtract parses riojoy.xcf (a GIMP-format binary
reader, no GIMP needed) into the 119-cell regions.json: per-layer offsets/size/
font/colour, with 90 deg CCW rotation on a-00 + b-10..b-1F. Base image riojoy.png.
NOTE: the wallpaper positions are a VGA chroma-split display artifact (6 displays),
not the cockpit's logical layout.

Mapping editor (first cut) — RioJoy.Tray/Editor/ProfileEditorForm renders the
config sheet's logical grid (SheetLayout parses the sheet CSV export). The iRIO
word is edited via ButtonBinding <-> RioMapEntry.Create (no hex bit-twiddling), with
a context-sensitive picker: keyboard keys by name (KeyCatalog VK names), joystick
Button N, hat direction, mouse/RIO-command enum names; modifiers only for keyboard.
Opened from the tray ("Edit profile..."). The sheet-grid layout is a starting point
that needs rework from a better-formatted source.

~220 xUnit tests green. Docs (PLAN.md, README) updated.

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

src/RioJoy.Overlay/ProfileWallpaperGenerator.cs

@@ -0,0 +1,56 @@
+using RioJoy.Core.Overlay;
+using SkiaSharp;
+
+namespace RioJoy.Overlay;
+
+/// <summary>
+/// Generates a profile's cockpit wallpaper: renders a label set onto the overlay
+/// template's base image and writes a PNG. Resolves the template's
+/// <see cref="OverlayTemplate.BaseImagePath"/> relative to the template file's
+/// directory (so a <c>regions.json</c> + sibling <c>riojoy.png</c> work as a unit).
+/// The runtime calls this on profile activation; an editor can call it for preview.
+/// </summary>
+public sealed class ProfileWallpaperGenerator
+{
+    private readonly SkiaOverlayRenderer _renderer;
+
+    public ProfileWallpaperGenerator(SkiaOverlayRenderer? renderer = null) =>
+        _renderer = renderer ?? new SkiaOverlayRenderer();
+
+    /// <summary>
+    /// Render <paramref name="labels"/> onto the template's base image and write a
+    /// PNG to <paramref name="outputPath"/>; returns the output path.
+    /// </summary>
+    /// <param name="templateDirectory">
+    /// Directory the template's relative <see cref="OverlayTemplate.BaseImagePath"/>
+    /// is resolved against (normally the folder holding the regions.json).
+    /// </param>
+    public string Generate(
+        OverlayTemplate template,
+        string templateDirectory,
+        IReadOnlyDictionary<string, string> labels,
+        string outputPath,
+        OverlayLayoutOptions? options = null)
+    {
+        ArgumentNullException.ThrowIfNull(template);
+        ArgumentNullException.ThrowIfNull(labels);
+        ArgumentException.ThrowIfNullOrWhiteSpace(outputPath);
+        if (string.IsNullOrWhiteSpace(template.BaseImagePath))
+            throw new InvalidOperationException("OverlayTemplate.BaseImagePath is not set.");
+
+        string basePath = Path.IsPathRooted(template.BaseImagePath)
+            ? template.BaseImagePath
+            : Path.Combine(templateDirectory, template.BaseImagePath);
+
+        using SKBitmap baseImage = SKBitmap.Decode(basePath)
+            ?? throw new InvalidOperationException($"Could not decode base image: {basePath}");
+
+        byte[] png = _renderer.RenderToPng(template, labels, baseImage, options);
+
+        string? dir = Path.GetDirectoryName(Path.GetFullPath(outputPath));
+        if (!string.IsNullOrEmpty(dir))
+            Directory.CreateDirectory(dir);
+        File.WriteAllBytes(outputPath, png);
+        return outputPath;
+    }
+}