Make the device status card always visible, not just on Stats

Moved out of the Stats tab's side column into a new horizontal bar
shared by every frame page (Photos/Configuration/Stats), sitting
between the page title and the tabs so it's on screen regardless of
which tab is active.

_device_status_bar.html is a new partial included via a device_status
block in app_base.html; device_status_bar.js is the fetch/render/poll
logic extracted from frame_stats.js and adapted to a wrapping row of
label/value pairs instead of a stacked list. frame_stats.html's Device
card and now-single-card .side-col are gone -- Battery history and
Lifetime stats just stack directly.

server/app/templates/frame_photos.html

@@ -3,6 +3,7 @@
 {% block title %}{{ frame.name or "Frame" }} · Photos{% endblock %}
 {% block page_title %}{{ frame.name or "Frame " ~ frame.id }}{% endblock %}
 
+{% block device_status %}{% include "_device_status_bar.html" %}{% endblock %}
 {% block tabs %}{% include "_frame_tabs.html" %}{% endblock %}
 
 {% block content %}
@@ -55,6 +56,7 @@
 
 {% block scripts %}
   <script>window.FRAME_API = {{ ("/api/frames/" ~ frame.id) | tojson }};</script>
+  <script src="/static/device_status_bar.js"></script>
   <script src="/static/queue.js"></script>
   <script src="/static/frame_photos.js"></script>
 {% endblock %}