Feature: HTMX + Jinja2 Frontend ersetzt Next.js komplett

- Kein Node.js, kein npm, kein Build-Schritt mehr
- HTMX 2.0.4 + PicoCSS 2 vendored in backend/static/
- Jinja2 Templates für alle 9 Seiten (Dashboard, ZFS, Snapshots,
  Shares, Identities, Logs, Services, Navigator, Login)
- HTMX Fragments für Live-Updates (30s Polling Dashboard)
- JWT als httpOnly Cookie statt localStorage
- Disk Usage zeigt TB/PB korrekt (Jinja2 serverseitig formatiert)
- Update-safe: nur Python-Deps, keine npm-Abhängigkeiten

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

backend/templates/dashboard.html

@@ -0,0 +1,53 @@
+{% extends "base.html" %}
+{% block title %}Dashboard – ZMB Webui{% endblock %}
+{% block content %}
+<div style="display:flex;align-items:center;justify-content:space-between;margin-bottom:1.5rem">
+  <div>
+    <h2 style="margin:0">Dashboard</h2>
+    <small style="color:var(--pico-muted-color)">{{ hostname }}</small>
+  </div>
+  <span class="htmx-indicator" id="spinner">&#9696; aktualisiert...</span>
+</div>
+
+<!-- Schnellstatistiken (alle 30s) -->
+<div class="grid-stats" id="quick-stats"
+     hx-get="/fragments/quick-stats"
+     hx-trigger="load, every 30s"
+     hx-indicator="#spinner">
+  <div class="stat-card"><h3>Lädt...</h3><p class="value">–</p></div>
+</div>
+
+<hr>
+
+<!-- Pools -->
+<h3>Storage Pools</h3>
+<div id="pools"
+     hx-get="/fragments/pools"
+     hx-trigger="load, every 30s"
+     hx-indicator="#spinner">
+  <p aria-busy="true">Lade Pools...</p>
+</div>
+
+<hr>
+
+<!-- Disk Usage -->
+<h3>Disk Usage</h3>
+<div id="disk-usage"
+     hx-get="/fragments/disk-usage"
+     hx-trigger="load"
+     hx-indicator="#spinner">
+  <p aria-busy="true">Lade...</p>
+</div>
+
+<hr>
+
+<!-- Netzwerk -->
+<h3>Network Traffic</h3>
+<div id="net-traffic"
+     hx-get="/fragments/net-traffic"
+     hx-trigger="load, every 10s"
+     hx-indicator="#spinner">
+  <p aria-busy="true">Lade...</p>
+</div>
+
+{% endblock %}