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/js/api.js

@@ -0,0 +1,78 @@
+// Accès aux routes exposées par le serveur axum et petits utilitaires partagés
+// par les web components du dashboard.
+
+export const endpoints = {
+  jobs: "/jobs",
+  reviews: "/dedup",
+  lifecycle: "/events",
+  jobEvents: (id) => `/jobs/${id}/events`,
+};
+
+async function getJson(url) {
+  const response = await fetch(url, { headers: { accept: "application/json" } });
+  if (!response.ok) {
+    throw new Error(`${url} → ${response.status}`);
+  }
+  return response.json();
+}
+
+export const fetchJobs = () => getJson(endpoints.jobs);
+export const fetchReviews = () => getJson(endpoints.reviews);
+
+// Ouvre un flux SSE et route les évènements nommés vers les callbacks fournis.
+// Les évènements du serveur sont nommés (`lifecycle`, `progress`, `gap`), donc
+// `addEventListener("message")` ne suffit pas : il faut écouter par nom.
+export function subscribe(url, handlers = {}) {
+  const source = new EventSource(url);
+
+  const onData = (name, handler) => {
+    if (handler) {
+      source.addEventListener(name, (event) => handler(JSON.parse(event.data)));
+    }
+  };
+
+  if (handlers.onOpen) source.addEventListener("open", () => handlers.onOpen());
+  if (handlers.onError) source.addEventListener("error", () => handlers.onError());
+  onData("lifecycle", handlers.onLifecycle);
+  onData("progress", handlers.onProgress);
+  if (handlers.onGap) {
+    source.addEventListener("gap", (event) => handlers.onGap(Number(event.data)));
+  }
+
+  return source;
+}
+
+export function escapeHtml(value) {
+  return String(value ?? "").replace(/[&<>"']/g, (char) => ({
+    "&": "&amp;",
+    "<": "&lt;",
+    ">": "&gt;",
+    '"': "&quot;",
+    "'": "&#39;",
+  })[char]);
+}
+
+// Horodatage relatif (« il y a 3 min »), tolérant sur les valeurs absentes.
+export function relativeTime(value) {
+  if (!value) return "—";
+  const then = Date.parse(value);
+  if (Number.isNaN(then)) return "—";
+
+  const seconds = Math.round((then - Date.now()) / 1000);
+  const steps = [
+    ["year", 60 * 60 * 24 * 365],
+    ["month", 60 * 60 * 24 * 30],
+    ["day", 60 * 60 * 24],
+    ["hour", 60 * 60],
+    ["minute", 60],
+    ["second", 1],
+  ];
+
+  const formatter = new Intl.RelativeTimeFormat("en", { numeric: "auto" });
+  for (const [unit, size] of steps) {
+    if (Math.abs(seconds) >= size || unit === "second") {
+      return formatter.format(Math.round(seconds / size), unit);
+    }
+  }
+  return "—";
+}