Add vue-router, login/setup flow and backend logging

Refactor frontend to route-based navigation with vue-router, add
system setup and login pages with API integration. Add structured
logging, access-log middleware and startup lifecycle to FastAPI
backend.

web/src/assets/styles/app.css

@@ -4,6 +4,68 @@
   grid-template-columns: 220px minmax(0, 1fr);
   background: var(--bg);
 }
+
+.boot-state {
+  min-height: 100dvh;
+  display: grid;
+  place-items: center;
+  padding: 24px;
+  background:
+    radial-gradient(circle at top left, rgba(16, 185, 129, 0.16), transparent 24rem),
+    radial-gradient(circle at bottom right, rgba(59, 130, 246, 0.14), transparent 28rem),
+    #f8fafc;
+}
+
+.boot-card {
+  width: min(560px, 100%);
+  padding: 36px;
+  border-radius: 8px;
+  border: 1px solid rgba(148, 163, 184, 0.22);
+  background: rgba(255, 255, 255, 0.88);
+  box-shadow: 0 24px 60px rgba(15, 23, 42, 0.12);
+  display: grid;
+  gap: 14px;
+}
+
+.boot-card h1 {
+  font-size: 28px;
+}
+
+.boot-card p {
+  color: var(--muted);
+  line-height: 1.7;
+}
+
+.boot-badge {
+  display: inline-flex;
+  width: fit-content;
+  min-height: 28px;
+  align-items: center;
+  padding: 0 10px;
+  border-radius: 999px;
+  background: rgba(16, 185, 129, 0.12);
+  color: #059669;
+  font-size: 12px;
+  font-weight: 800;
+  letter-spacing: 0.12em;
+}
+
+.boot-badge-error {
+  background: rgba(239, 68, 68, 0.12);
+  color: #b91c1c;
+}
+
+.boot-action {
+  width: fit-content;
+  min-height: 44px;
+  padding: 0 18px;
+  border: 1px solid transparent;
+  border-radius: 8px;
+  background: #0f172a;
+  color: #fff;
+  font-weight: 700;
+}
+
 .main { min-width: 0; display: grid; grid-template-rows: auto auto minmax(0, 1fr); }
 .main.overview-main {
   grid-template-rows: auto minmax(0, 1fr);