feat: Remote Nodes Foundation (Strategy B) - Add nodes table with auto-seeded default local node in DatabaseService - Create NodeRegistry service for multi-instance Docker daemon connections - Add 6 Node management API endpoints (CRUD + test connection) - Create NodeManager component with table UI and connection testing - Add NodeContext for frontend-wide active node state management - Add node switcher dropdown to sidebar (visible when >1 node) - Add Nodes tab to Settings Hub

frontend/src/context/NodeContext.tsx

@@ -0,0 +1,83 @@
+import React, { createContext, useContext, useState, useEffect, useCallback } from 'react';
+import { apiFetch } from '@/lib/api';
+
+export interface Node {
+  id: number;
+  name: string;
+  type: 'local' | 'remote';
+  host: string;
+  port: number;
+  compose_dir: string;
+  is_default: boolean;
+  status: 'online' | 'offline' | 'unknown';
+  created_at: number;
+}
+
+interface NodeContextType {
+  nodes: Node[];
+  activeNode: Node | null;
+  setActiveNode: (node: Node) => void;
+  refreshNodes: () => Promise<void>;
+  isLoading: boolean;
+}
+
+const NodeContext = createContext<NodeContextType | undefined>(undefined);
+
+export function NodeProvider({ children }: { children: React.ReactNode }) {
+  const [nodes, setNodes] = useState<Node[]>([]);
+  const [activeNode, setActiveNodeState] = useState<Node | null>(null);
+  const [isLoading, setIsLoading] = useState(true);
+
+  const refreshNodes = useCallback(async () => {
+    try {
+      const res = await apiFetch('/nodes');
+      if (res.ok) {
+        const data = await res.json();
+        setNodes(data);
+
+        // If no active node is set, select the default node
+        if (!activeNode) {
+          const defaultNode = data.find((n: Node) => n.is_default);
+          if (defaultNode) {
+            setActiveNodeState(defaultNode);
+          } else if (data.length > 0) {
+            setActiveNodeState(data[0]);
+          }
+        } else {
+          // Refresh the active node's data in case its status changed
+          const updatedActive = data.find((n: Node) => n.id === activeNode.id);
+          if (updatedActive) {
+            setActiveNodeState(updatedActive);
+          }
+        }
+      }
+    } catch (error) {
+      console.error('Failed to fetch nodes:', error);
+    } finally {
+      setIsLoading(false);
+    }
+  }, [activeNode]);
+
+  const setActiveNode = useCallback((node: Node) => {
+    setActiveNodeState(node);
+    localStorage.setItem('sencho-active-node', String(node.id));
+  }, []);
+
+  useEffect(() => {
+    refreshNodes();
+  }, []);
+
+  return (
+    <NodeContext.Provider value={{ nodes, activeNode, setActiveNode, refreshNodes, isLoading }}>
+      {children}
+    </NodeContext.Provider>
+  );
+}
+
+export function useNodes() {
+  const context = useContext(NodeContext);
+  if (!context) {
+    throw new Error('useNodes must be used within a NodeProvider');
+  }
+  return context;
+}