Add CI/CD pipelines for Lendair (iOS + web) [FRE-4690]

- iOS: swift lint, build verification, and test on PR
- Web: typecheck, vitest tests, build, and Vercel deployment (ready for web project)
- Package.swift: defines Lendair as buildable Swift package
- Test target: LendairTests with XCTest boilerplate

Co-Authored-By: Paperclip <noreply@paperclip.ing>

Lendair/LendairTests/LendairTests.swift

@@ -0,0 +1,7 @@
+import XCTest
+
+class LendairTests: XCTestCase {
+    func testPackageLoads() throws {
+        XCTAssertTrue(true)
+    }
+}

Lendair/Package.swift

@@ -0,0 +1,33 @@
+// swift-tools-version: 5.9
+import PackageDescription
+
+let package = Package(
+    name: "Lendair",
+    platforms: [
+        .iOS(.v16),
+        .macOS(.v13)
+    ],
+    products: [
+        .library(
+            name: "Lendair",
+            targets: ["Lendair"]
+        )
+    ],
+    targets: [
+        .target(
+            name: "Lendair",
+            path: ".",
+            sources: [
+                "Models",
+                "Services",
+                "ViewModels",
+                "Views"
+            ]
+        ),
+        .testTarget(
+            name: "LendairTests",
+            dependencies: ["Lendair"],
+            path: "LendairTests"
+        )
+    ]
+)