feat: add http, snmp, docker plugins; new widgets and routes for traefik/unifi/ups

- Add HTTP monitor plugin: endpoint checking with status history, latency tracking, time-range views
- Add SNMP plugin: OID polling, device management, metric recording
- Add Docker plugin: container status, resource usage, widget
- Traefik: access log widget, request chart widget, expanded routes
- UniFi: clients widget, devices widget, expanded poll routes
- UPS: history widget, additional routes
- Update plugin index with new entries

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

http/__init__.py

@@ -0,0 +1,24 @@
+# plugins/http/__init__.py
+from __future__ import annotations
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from quart import Quart
+
+_app: "Quart | None" = None
+
+
+def setup(app: "Quart") -> None:
+    global _app
+    _app = app
+    from .models import HttpMonitor, HttpResult  # noqa: F401
+
+
+def get_scheduled_tasks() -> list:
+    from .scheduler import make_task
+    return [make_task(_app)]
+
+
+def get_blueprint():
+    from .routes import http_bp
+    return http_bp