Add lead workflows, PDF signing, AR projects and photo gallery integration

GasTankAR/Domain/AR/ARProject.swift

@@ -0,0 +1,32 @@
+import Foundation
+
+/// Neutral projection for project selection. Persistence and customer associations
+/// belong to the host application's service.
+struct ARProject: Identifiable, Equatable {
+    let id: UUID
+    let name: String
+    let tank: Tank
+    let createdAt: Date
+    let source: Source
+    let reference: String?
+
+    enum Source { case supplied, custom }
+}
+
+@MainActor
+protocol ARProjectsProviding {
+    func updateProject(id: UUID, name: String, tank: Tank) throws -> ARProject
+    func deleteProject(id: UUID) throws
+    func loadProjects() throws -> [ARProject]
+    func createProject(name: String, tank: Tank) throws -> ARProject
+}
+
+nonisolated extension TankSize {
+    var volumeTitle: String {
+        switch self {
+        case .t1_2: "2.700 l"
+        case .t2_1: "4.850 l"
+        case .t2_9: "6.400 l"
+        }
+    }
+}