feat(web): Projektgerüst, Router, Grundlayout

Vite + TypeScript ohne UI-Framework in web/, exakte Versionen, History-Router
(matchRoute, navigate, startRouter mit Cleanup, a[data-link], popstate),
Grundlayout mit Kopfzeile, Fußzeile und Platzhalterseiten.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/styles.css

@@ -0,0 +1,108 @@
+:root {
+  --bg: #0F1828;
+  --panel: #162133;
+  --panel-2: #1B2738;
+  --line: #2A3A52;
+  --line-strong: #3D5576;
+  --sel-bg: #1F3150;
+  --sel-line: #8FB4E8;
+  --text: #E8EEF7;
+  --muted: #9DB0C8;
+  --primary: #2A4566;
+  --primary-hover: #34557C;
+  --danger: #E5484D;
+  --radius: 14px;
+
+  color-scheme: dark;
+}
+
+*,
+*::before,
+*::after {
+  box-sizing: border-box;
+}
+
+html,
+body {
+  margin: 0;
+}
+
+body {
+  display: flex;
+  flex-direction: column;
+  min-height: 100vh;
+  background: var(--bg);
+  color: var(--text);
+  font-family: 'Nunito Sans Variable', system-ui, sans-serif;
+  font-size: 16px;
+  line-height: 1.5;
+}
+
+a {
+  color: var(--sel-line);
+}
+
+:focus-visible {
+  outline: 2px solid var(--sel-line);
+  outline-offset: 2px;
+}
+
+#app-header {
+  display: flex;
+  align-items: center;
+  gap: 24px;
+  padding: 14px 20px;
+  background: var(--panel);
+  border-bottom: 1px solid var(--line);
+}
+
+.brand {
+  color: var(--text);
+  font-size: 1.35rem;
+  font-weight: 800;
+  letter-spacing: 0.01em;
+  text-decoration: none;
+}
+
+.app-nav a {
+  color: var(--muted);
+  font-weight: 600;
+  text-decoration: none;
+}
+
+.app-nav a:hover {
+  color: var(--text);
+}
+
+#account-slot {
+  display: flex;
+  align-items: center;
+  margin-left: auto;
+}
+
+#app-root {
+  flex: 1;
+  width: 100%;
+  max-width: 1280px;
+  margin: 0 auto;
+  padding: 24px 20px;
+}
+
+#app-root h1 {
+  margin: 0 0 16px;
+  font-size: 1.6rem;
+  line-height: 1.2;
+}
+
+#app-footer {
+  padding: 16px 20px;
+  border-top: 1px solid var(--line);
+  color: var(--muted);
+  font-size: 0.85rem;
+  text-align: center;
+}
+
+#app-footer p {
+  max-width: 900px;
+  margin: 0 auto;
+}