feat: add system metrics dashboard with resource monitoring

- Add system metrics endpoint (CPU load, memory, swap, network traffic)
- Collect metrics from /proc and /sys (no subprocess required)
- Overhaul dashboard to pull from per-subsystem models
- Remove deprecated /status/all monolithic endpoint
- Improve networkd import to handle optional priority prefix
- Fix CSS duplicate .grid-4 rule and unused dashboard imports

webui/api/status.py

@@ -10,7 +10,7 @@ import logging
 from flask import Blueprint
 
 from daemon.client import get, post
-from daemon.iface import GET_STATUS_PENDING, POST_STATUS_APPLY_ALL
+from daemon.iface import GET_STATUS_PENDING, GET_SYSTEM_METRICS, POST_STATUS_APPLY_ALL
 from webui.api.common import _error, _ok
 
 logger = logging.getLogger(__name__)
@@ -49,3 +49,20 @@ def apply_all():
     except RuntimeError as exc:
         logger.error("Failed to apply all pending changes: %s", exc)
         return _error(str(exc), 500)
+
+
+@bp.route("/system-metrics", methods=["GET"])
+def system_metrics():
+    """Retrieve system-wide metrics.
+
+    Endpoint:
+        GET /api/status/system-metrics
+
+    Returns:
+        JSON response with CPU load, memory usage, and network traffic stats.
+    """
+    try:
+        return _ok(get(GET_SYSTEM_METRICS))
+    except RuntimeError as exc:
+        logger.error("Failed to get system metrics: %s", exc)
+        return _error(str(exc), 500)