better main view, add initial post view

Signed-off-by: William Casarin <jb55@jb55.com>

damus/Views/PostView.swift

@@ -0,0 +1,20 @@
+//
+//  Post.swift
+//  damus
+//
+//  Created by William Casarin on 2022-04-03.
+//
+
+import SwiftUI
+
+struct PostView: View {
+    var body: some View {
+        Text("New post")
+    }
+}
+
+struct Post_Previews: PreviewProvider {
+    static var previews: some View {
+        PostView()
+    }
+}