Add live dashboard with SSE job events

Expose /jobs, /dedup, and /events routes backed by a new EventBus that
broadcasts job lifecycle and per-job progress over SSE. Serve a static
dashboard from front/ that lists pending and in-progress jobs, streams
agent activity, and shows completed reviews.

Also add migrate-apply/migrate-generate scripts that load .env, update
the Containerfile to ship the front assets and use the apply script, and
refresh the roadmap.

front/index.html

@@ -0,0 +1,46 @@
+<!DOCTYPE html>
+<html lang="en" data-theme="dark">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <meta name="theme-color" content="#0b1520">
+  <link rel="icon" type="image/png" sizes="512x512" href="/favicon.png">
+  <link rel="apple-touch-icon" href="/favicon.png">
+  <meta name="description" content="Steep dashboard — pending jobs, work in progress, and completed reviews, live over SSE.">
+  <title>Steep — Dashboard</title>
+  <link rel="stylesheet" href="/css/dashboard.css">
+  <script>
+    // Applique le thème enregistré avant le premier rendu, pour éviter un flash.
+    try {
+      const savedTheme = localStorage.getItem("steep-theme");
+      if (savedTheme === "light" || savedTheme === "dark") {
+        document.documentElement.dataset.theme = savedTheme;
+      }
+    } catch (_) {}
+  </script>
+</head>
+<body>
+  <header class="site-header">
+    <nav class="nav container" aria-label="Main navigation">
+      <a class="wordmark" href="/" aria-label="Steep dashboard"><span class="wordmark-mark">S</span> STEEP</a>
+      <div class="nav-links">
+        <a class="nav-cta" href="https://gitea.qpismont.fr/qpismont/herald">View source <span class="arrow" aria-hidden="true">↗</span></a>
+        <steep-theme-toggle></steep-theme-toggle>
+      </div>
+    </nav>
+  </header>
+
+  <main id="top" class="container">
+    <steep-dashboard></steep-dashboard>
+  </main>
+
+  <footer>
+    <div class="container footer-inner">
+      <span><span class="footer-brand">STEEP</span> · Let your code steep.</span>
+      <span>Built with Rust · <a href="https://gitea.qpismont.fr/qpismont/herald">Source on Gitea</a></span>
+    </div>
+  </footer>
+
+  <script type="module" src="/js/dashboard.js"></script>
+</body>
+</html>