initial commit: Proximity iOS app proposal, full Swift code scaffold, reference backend, testing docs, generated Xcode project

Proximity/Views/SignInView.swift

@@ -0,0 +1,60 @@
+import SwiftUI
+
+/// The sign-in screen.
+///
+/// Auth here is about **account identity** — who you are to the app — not
+/// about what you reveal to others. The copy makes clear that signing in
+/// never makes you discoverable; you must separately choose to be present.
+struct SignInView: View {
+    @EnvironmentObject private var authService: AuthService
+
+    var body: some View {
+        VStack(spacing: 32) {
+            Spacer()
+
+            VStack(spacing: 12) {
+                Image(systemName: "dot.radiowaves.left.and.right")
+                    .font(.system(size: 64))
+                    .foregroundColor(.green)
+                Text("Proximity")
+                    .font(.largeTitle.bold())
+                Text("A social network you can only enter\nby being physically present.")
+                    .multilineTextAlignment(.center)
+                    .foregroundColor(.secondary)
+            }
+
+            Spacer()
+
+            VStack(spacing: 12) {
+                SignInWithAppleButton { request in
+                    request.requestedScopes = [.fullName, .email]
+                } onCompletion: { result in
+                    // Handled via AppleAuthProvider in AuthService.
+                }
+                .frame(height: 50)
+                .signInWithAppleButtonStyle(.black)
+
+                Button {
+                    Task { try? await authService.signIn(with: .google) }
+                } label: {
+                    HStack {
+                        Image(systemName: "g.circle.fill")
+                        Text("Continue with Google")
+                    }
+                    .frame(maxWidth: .infinity)
+                    .padding()
+                    .background(Color(.secondarySystemBackground))
+                    .clipShape(RoundedRectangle(cornerRadius: 12))
+                }
+                .buttonStyle(.plain)
+            }
+            .padding(.horizontal)
+
+            Text("Signing in never makes you discoverable.\nYou choose to be present separately.")
+                .font(.caption)
+                .foregroundColor(.secondary)
+                .multilineTextAlignment(.center)
+                .padding(.bottom, 24)
+        }
+    }
+}