Add update-vendor.sh symlink support, unify install.sh vendor flow

- update-vendor.sh now creates webui/vendor symlinks (htm.js)
- install.sh calls update-vendor.sh after package install
- Add vendor/.empty and webui/vendor/.empty as directory placeholders in git

webui/api/status.py

@@ -0,0 +1,51 @@
+"""Aggregate status API blueprint.
+
+Exposed at /api/status/* and delegates all operations to vacuum-walld.
+"""
+
+from __future__ import annotations
+
+import logging
+
+from flask import Blueprint
+
+from daemon.client import get, post
+from daemon.iface import GET_STATUS_PENDING, POST_STATUS_APPLY_ALL
+from webui.api.common import _error, _ok
+
+logger = logging.getLogger(__name__)
+bp = Blueprint("status", __name__)
+
+
+@bp.route("/pending", methods=["GET"])
+def pending():
+    """Retrieve aggregate pending changes across all subsystems.
+
+    Endpoint:
+        GET /api/status/pending
+
+    Returns:
+        JSON response with per-subsystem pending status and total change count.
+    """
+    try:
+        return _ok(get(GET_STATUS_PENDING))
+    except RuntimeError as exc:
+        logger.error("Failed to get pending status: %s", exc)
+        return _error(str(exc), 500)
+
+
+@bp.route("/apply-all", methods=["POST"])
+def apply_all():
+    """Apply pending changes for all subsystems in dependency order.
+
+    Endpoint:
+        POST /api/status/apply-all
+
+    Returns:
+        JSON response with applied subsystems list and any errors encountered.
+    """
+    try:
+        return _ok(post(POST_STATUS_APPLY_ALL))
+    except RuntimeError as exc:
+        logger.error("Failed to apply all pending changes: %s", exc)
+        return _error(str(exc), 500)