Move rolling stock and physics into the domain

VehicleDatabase becomes VehicleCatalog, Physics becomes VehiclePhysics, and the
textures.txt and .fiz parsers move to Infrastructure. GameLibrary replaces the
GameData singleton.

StarterNG/Application/Abstractions/IFileSystem.cs

@@ -51,5 +51,11 @@ public interface IFileSystem
     /// <summary>Top-level directories, empty when the directory does not exist.</summary>
     IReadOnlyList<string> GetDirectories(string path);
 
+    /// <summary>
+    /// Files matching the pattern anywhere below the path. Empty when the
+    /// directory does not exist.
+    /// </summary>
+    IReadOnlyList<string> GetFilesRecursive(string path, string searchPattern);
+
     DateTime GetLastWriteTimeUtc(string path);
 }

StarterNG/Application/Abstractions/IMiniTextureIndex.cs

@@ -0,0 +1,19 @@
+namespace StarterNG.Application.Abstractions;
+
+/// <summary>
+/// The thumbnails in textures/mini, looked up by name. Backed by one directory
+/// scan; a name with no bitmap falls back to the generic "other" thumbnail.
+/// </summary>
+public interface IMiniTextureIndex
+{
+    /// <summary>Builds the index up front, off the UI thread.</summary>
+    void Preload();
+
+    bool Has(string? miniName);
+
+    /// <summary>Bitmap for the name, the fallback thumbnail, or null when neither exists.</summary>
+    string? PathFor(string? miniName);
+
+    /// <summary>The generic thumbnail shown for unknown stock.</summary>
+    string? FallbackPath { get; }
+}

StarterNG/Application/Abstractions/IPhysicsRepository.cs

@@ -0,0 +1,21 @@
+using StarterNG.Domain.Vehicles;
+
+namespace StarterNG.Application.Abstractions;
+
+/// <summary>
+/// Looks up the .fiz physics of a vehicle type by model name.
+/// </summary>
+public interface IPhysicsRepository
+{
+    /// <summary>Indexes the installation's .fiz files up front, off the UI thread.</summary>
+    void Preload();
+
+    /// <summary>How many vehicle types were indexed; zero means a broken installation.</summary>
+    int IndexedCount { get; }
+
+    /// <summary>
+    /// Physics for a model name (with or without extension), or null when the
+    /// installation has no .fiz for it.
+    /// </summary>
+    VehiclePhysics? For(string? dataFolder, string? model);
+}

StarterNG/Application/Abstractions/IVehicleRepository.cs

@@ -0,0 +1,17 @@
+using StarterNG.Domain.Vehicles;
+
+namespace StarterNG.Application.Abstractions;
+
+/// <summary>
+/// Reads the installation's rolling stock. The only route from the dynamic/
+/// folder to a <see cref="VehicleCatalog"/>.
+/// </summary>
+public interface IVehicleRepository
+{
+    /// <summary>
+    /// Fills the catalogue from every textures.txt under dynamic/. Returns the
+    /// number of liveries read, which the caller uses to spot an installation
+    /// with no rolling stock at all.
+    /// </summary>
+    int Load(VehicleCatalog catalog);
+}