Add font infrastructure

Sources/SwiftUIMath/Font.swift

@@ -0,0 +1,35 @@
+import Foundation
+
+extension Math {
+  public struct Font: Hashable, Sendable {
+    public struct Name: Hashable, Sendable, RawRepresentable, ExpressibleByStringLiteral {
+      public let rawValue: String
+
+      public init(rawValue: String) {
+        self.rawValue = rawValue
+      }
+
+      public init(stringLiteral value: StringLiteralType) {
+        self.rawValue = value
+      }
+    }
+
+    public let name: Name
+    public let size: CGFloat
+  }
+}
+
+extension Math.Font.Name {
+  public static let latinModern: Self = "latinmodern-math"
+  public static let kpMathLight: Self = "KpMath-Light"
+  public static let kpMathSans: Self = "KpMath-Sans"
+  public static let xits: Self = "xits-math"
+  public static let termes: Self = "texgyretermes-math"
+  public static let asana: Self = "Asana-Math"
+  public static let euler: Self = "Euler-Math"
+  public static let fira: Self = "FiraMath-Regular"
+  public static let notoSans: Self = "NotoSansMath-Regular"
+  public static let libertinus: Self = "LibertinusMath-Regular"
+  public static let garamond: Self = "Garamond-Math"
+  public static let leteSans: Self = "LeteSansMath"
+}