feat: add OPC (One Person Company) management system with Kanban board

Phase 1 MVP implementation:
- PostgreSQL database schema for tasks, agents, executions, time tracking
- Backend API: task CRUD, agent management, automatic time tracking
- Frontend: Kanban board with drag-and-drop (Parking Lot → In Progress → Done)
- Task modal for creating/editing tasks with tags, priority, assignee
- 3 core agents seeded: PM, CTO, COO
- Agent approval workflow: CxO level requires approval, others auto-execute
- Automatic time tracking: starts on in_progress, stops on done
- RBAC integration: OPC page accessible to admin/member roles

Features:
- Drag-and-drop tasks between columns
- Assign tasks to humans or AI agents
- Priority badges (low, medium, high, urgent)
- Tags and due dates
- Task history tracking
- Time entry tracking with automatic timer
- Agent execution records with approval workflow

Next steps:
- Initialize OPC database on NAS
- Implement agent executor service
- Add WebSocket for real-time updates
- Add email notifications
- Add PDF invoice generation

dashboard/frontend/src/components/opc/KanbanBoard.svelte

@@ -0,0 +1,40 @@
+<script>
+  import KanbanColumn from "./KanbanColumn.svelte";
+  import { moveTask } from "../../lib/opc-api.js";
+
+  let { tasks = [], agents = [], onEdit, onDelete, onAssign, onTaskMoved } = $props();
+
+  const columns = [
+    { id: "parking_lot", title: "Parking Lot", status: "parking_lot" },
+    { id: "in_progress", title: "In Progress", status: "in_progress" },
+    { id: "done", title: "Done", status: "done" }
+  ];
+
+  function getTasksByStatus(status) {
+    return tasks.filter(t => t.status === status);
+  }
+
+  async function handleDrop(taskId, newStatus) {
+    try {
+      await moveTask(taskId, newStatus);
+      onTaskMoved?.(taskId, newStatus);
+    } catch (e) {
+      alert("Failed to move task: " + e.message);
+    }
+  }
+</script>
+
+<div class="grid grid-cols-1 md:grid-cols-3 gap-4 h-full">
+  {#each columns as column}
+    <KanbanColumn
+      title={column.title}
+      status={column.status}
+      tasks={getTasksByStatus(column.status)}
+      {agents}
+      {onEdit}
+      {onDelete}
+      {onAssign}
+      onDrop={handleDrop}
+    />
+  {/each}
+</div>