Allow local authentication with LOCAL_AUTHENTICATION=1

You can touch `tmp/local-auth.txt` to persist this setting.

app/views/sessions/new.html.erb

@@ -0,0 +1,30 @@
+<% @page_title = "Sign in" %>
+
+<div class="panel shadow center margin-block-double <%= "shake" if flash[:alert] %>" style="--panel-size: 55ch;">
+  <h1 class="txt-xx-large margin-block-end-double">Fizzy</h1>
+
+  <%= form_with url: session_path, class: "flex flex-column gap txt-large" do |form| %>
+    <div class="flex align-center gap">
+      <label class="flex align-center gap input input--actor">
+        <%= form.email_field :email_address, required: true, class: "input full-width", autofocus: true, autocomplete: "username", placeholder: "Enter your email address" %>
+        <%= icon_tag "email", class: "txt-large" %>
+      </label>
+    </div>
+
+    <div class="flex align-center gap">
+      <label class="flex align-center gap input input--actor">
+        <%= form.password_field :password, required: true, class: "input full-width", autocomplete: "current-password", placeholder: "Enter your password", maxlength: 72 %>
+        <%= icon_tag "password", class: "txt-large" %>
+      </label>
+    </div>
+
+    <button type="submit" id="log_in" class="btn btn--reversed center">
+      <%= icon_tag "arrow-right" %>
+      <span class="for-screen-reader">Sign in</span>
+    </button>
+  <% end %>
+</div>
+
+<% content_for :footer do %>
+  <div class="txt-align-center center margin-block-double txt-subtle">Fizzy&trade; version 0</div>
+<% end %>