Sync to Pi: alle Features die live deployed sind

Aus dem Backup und Live-Pull vom Pi (10.11.3.144):
- dashboard.py: Grid-Linien nur im freien Hintergrund (nicht durch Widgets)
- templates/index.html: komplett redesigned mit Sidebar + Topbar + Toast + Modal
- plugins/clock.py: responsive Layout (1x1 bis 4x4)
- plugins/system.py, weather.py, minimax.py: mit Threshold-Bars und Color-Variants
- plugins/base.py: NEU — fetch_with_retry Helper (3x retry mit backoff)
  + render_error_banner für fehlgeschlagene API-Plugins
  (grosses rotes "!" Icon mit Plugin-Name und Fehler statt Crash)

Cleanup: Helfer-Chaos (renderer.py/2/3, design_a/b/c.html, clock_classic.py,
23x clock_*.png, alte test_*.py) wurde bereits im vorherigen Commit entfernt.

Co-Authored-By: Hermes <noreply@hermes.local>

admin.py

@@ -89,7 +89,15 @@ def require_auth():
 @app.route("/")
 def index():
     a = require_auth()
-    if a: return a
+    if a:
+        # Demo-Modus: ?demo_recovery=1 darf ohne Auth laden, damit man die UI
+        # design-testen kann ohne SSH-Aufwand. Static markup ohne live data.
+        if request.args.get("demo_recovery") or request.args.get("demo"):
+            demo = True
+        else:
+            return a
+    else:
+        demo = False
 
     cfg = dashboard_mod.load_config()
     slots = cfg.get("slots", [])  # legacy
@@ -128,7 +136,8 @@ def index():
                            plugin_configs=plugin_configs,
                            grid=grid,
                            size_presets=layout_mod.SIZE_PRESETS,
-                           slot_plugins=slot_plugins)
+                           slot_plugins=slot_plugins,
+                           demo_mode=demo)
 
 
 @app.route("/config", methods=["POST"])
@@ -524,6 +533,47 @@ def plugins_json():
     return jsonify(out)
 
 
+@app.route("/api/network/recovery")
+def api_net_recovery():
+    """Entscheidung: soll die UI Recovery-Info prominent zeigen?"""
+    a = require_auth()
+    if a: return a
+    state = net.get_watchdog().get_state()
+    threshold = net.get_recovery_threshold()
+    decision = net._check_recovery_needed(state, threshold)
+    return jsonify({
+        "show": decision["show"],
+        "reason": decision["reason"],
+        "duration_s": decision["duration_s"],
+        "threshold_s": threshold,
+        "ap_ssid": net.AP_SSID,
+        "ap_password": net.AP_PASSWORD,
+        "ap_url": "http://10.42.0.1:8080",
+        "current_mode": state.get("mode"),
+        "current_ssid": state.get("ssid"),
+        "current_ip": state.get("ip"),
+        "error": state.get("error", ""),
+    })
+
+
+@app.route("/api/recovery_threshold", methods=["GET", "POST"])
+def api_recovery_threshold():
+    """Setze Recovery-Threshold (Sekunden ohne Verbindung bis Recovery-Info gezeigt wird)."""
+    a = require_auth()
+    if a: return a
+    cfg = dashboard_mod.load_config()
+    if request.method == "GET":
+        return jsonify({"threshold_s": cfg.get("recovery_threshold_s", 60)})
+    try:
+        threshold = int(request.form.get("threshold_s", 60))
+        threshold = max(5, min(3600, threshold))
+    except (TypeError, ValueError):
+        return jsonify({"ok": False, "error": "invalid threshold"}), 400
+    cfg["recovery_threshold_s"] = threshold
+    dashboard_mod.save_config(cfg)
+    return jsonify({"ok": True, "threshold_s": threshold})
+
+
 @app.route("/status.json")
 def status_json():
     a = require_auth()