feat: sync DB prefs, update history tab, configurable dashboard shortcuts

- auth store fetchMe(): sync theme/sidebar_position/lang from DB to localStorage+stores on login/refresh
- profilePage setters: PATCH /api/auth/preferences on every preference change
- updatesPage: add history tab (GET /api/updates/history) with job list, click to view output
- dashboardPage: load shortcuts from settings API, fall back to defaults if none configured
- settingsPage: new Raccourcis tab to add/remove/configure dashboard shortcuts (saved as JSON)
- settings.go: expose dashboard_shortcuts in publicSettings for GET/PUT access
- pages.css: add .history-table, .shortcut-row styles

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/css/pages.css

@@ -732,3 +732,44 @@
   display: block;
   line-height: 1;
 }
+
+/* ── Historique mises à jour ─────────────────────────────────────────────────── */
+.history-table { display: flex; flex-direction: column; gap: 0; }
+.history-header, .history-row {
+  display: grid;
+  grid-template-columns: 6rem 1fr 6rem 10rem 5rem;
+  gap: .5rem;
+  align-items: center;
+  padding: .5rem .75rem;
+}
+.history-header {
+  font-size: .75rem;
+  font-weight: 600;
+  color: var(--neu-text-muted);
+  text-transform: uppercase;
+  letter-spacing: .04em;
+  border-bottom: 1px solid var(--neu-border);
+}
+.history-row {
+  font-size: .85rem;
+  cursor: pointer;
+  border-bottom: 1px solid var(--neu-border);
+  transition: background .15s;
+}
+.history-row:last-child { border-bottom: none; }
+.history-row:hover { background: var(--neu-bg-hover); border-radius: var(--neu-radius); }
+.history-job { font-family: monospace; opacity: .7; }
+.history-status.running  { color: var(--neu-info); }
+.history-status.success  { color: var(--neu-success); }
+.history-status.error    { color: var(--neu-danger); }
+
+/* ── Éditeur de raccourcis ───────────────────────────────────────────────────── */
+.shortcuts-editor { display: flex; flex-direction: column; gap: .5rem; }
+.shortcut-row {
+  display: grid;
+  grid-template-columns: 9rem 1fr 1fr 2rem;
+  gap: .5rem;
+  align-items: center;
+}
+.shortcut-icon-sel { padding: .4rem .5rem; font-size: .85rem; }
+.shortcut-label, .shortcut-href { font-size: .85rem; }