Homepage (TDD slice 4): the pages, theme, and toggle

Red tests first, then the pages.
- tests/homepage_pages.bats: the pages reference the data + theme; no
  auto-refresh (Q41); no cursor alteration (Q28); the styling toggle strips
  to bare HTML (Q27); the footer shows the last master deployment datetime
  (Q43).
- index.html / admin.html: the user and admin pages. A grid of TUI panels,
  a summary line, the bare toggle, the deployed-at footer.
- app.js: reads status.json + services.json once (no auto-refresh), renders
  one panel per service for the page's category, the toggle, the footer.
- style.css: the terminal TUI theme (green-on-black, phosphor palette,
  scanlines) + a ?bare=1 mode that strips to unstyled HTML. No custom cursor.

Functionally verified with a Node DOM shim: 9 user panels, correct summary,
correct footer datetime.

shared/homepage/admin.html

@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1">
+<title>frank — admin</title>
+<link rel="stylesheet" href="style.css">
+</head>
+<body>
+<header class="top">
+  <span class="title">frank@home:~$ admin</span>
+  <a id="bare-toggle" class="toggle" href="?bare=1">bare</a>
+</header>
+<div id="summary" class="summary"></div>
+<main id="grid" class="grid"></main>
+<footer class="foot">
+  <span>last master deployment: <span id="deployed-at"></span></span>
+  <a href="/">home</a>
+</footer>
+<script src="deployed.js"></script>
+<script src="app.js"></script>
+</body>
+</html>