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/fragments/pools.html

@@ -0,0 +1,44 @@
+{% macro fmt_bytes(b) %}
+  {%- if b == 0 %}0 B
+  {%- elif b < 1048576 %}{{ "%.1f"|format(b/1024) }} KB
+  {%- elif b < 1073741824 %}{{ "%.1f"|format(b/1048576) }} MB
+  {%- elif b < 1099511627776 %}{{ "%.1f"|format(b/1073741824) }} GB
+  {%- else %}{{ "%.1f"|format(b/1099511627776) }} TB
+  {%- endif %}
+{%- endmacro %}
+
+{% if not pools %}
+<p>Keine ZFS Pools verfügbar.</p>
+{% else %}
+<div style="display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:1rem">
+{% for pool in pools %}
+  {% set pct = (pool.allocated / pool.size * 100)|int if pool.size else 0 %}
+  <article style="margin:0;padding:1rem">
+    <div style="display:flex;justify-content:space-between;align-items:center">
+      <strong>{{ pool.name }}</strong>
+      <span class="badge {% if pool.health == 'ONLINE' %}badge-green{% elif pool.health == 'DEGRADED' %}badge-yellow{% else %}badge-red{% endif %}">{{ pool.health }}</span>
+    </div>
+    <div class="progress-bar-wrap" style="margin:0.5rem 0">
+      <div class="progress-bar {% if pct > 85 %}bar-red{% elif pct > 70 %}bar-yellow{% else %}bar-blue{% endif %}" style="width:{{ pct }}%"></div>
+    </div>
+    <small style="color:var(--pico-muted-color)">
+      {{ fmt_bytes(pool.allocated) }} / {{ fmt_bytes(pool.size) }} ({{ pct }}%)
+    </small>
+    {% if pool.status and pool.status != 'ONLINE' %}
+    <p style="margin:0.5rem 0 0;font-size:0.8rem;color:#fca5a5">{{ pool.status }}</p>
+    {% endif %}
+    <div class="actions" style="margin-top:0.75rem">
+      <button class="outline secondary"
+              hx-post="/api/pools/{{ pool.name }}/scrub"
+              hx-confirm="Scrub für {{ pool.name }} starten?"
+              hx-target="closest article"
+              hx-swap="none">Scrub</button>
+      <button class="outline secondary"
+              hx-post="/api/pools/{{ pool.name }}/clear"
+              hx-confirm="Fehler für {{ pool.name }} löschen?"
+              hx-swap="none">Clear</button>
+    </div>
+  </article>
+{% endfor %}
+</div>
+{% endif %}