feat(18-03): create TaskDetailModal component for initiative detail

Controlled dialog showing full task metadata, dependencies, dependents,
and action buttons (Queue Task / Stop Task) with proper enable/disable
logic based on task status and dependency completion.

packages/web/src/components/TaskDetailModal.tsx

@@ -0,0 +1,170 @@
+import {
+  Dialog,
+  DialogContent,
+  DialogDescription,
+  DialogFooter,
+  DialogHeader,
+  DialogTitle,
+} from "@/components/ui/dialog";
+import { Button } from "@/components/ui/button";
+import { StatusBadge } from "@/components/StatusBadge";
+
+/** Serialized Task shape as returned by tRPC (Date serialized to string over JSON) */
+export interface SerializedTask {
+  id: string;
+  planId: string;
+  name: string;
+  description: string | null;
+  type: string;
+  priority: string;
+  status: string;
+  order: number;
+  createdAt: string;
+  updatedAt: string;
+}
+
+interface DependencyInfo {
+  name: string;
+  status: string;
+}
+
+interface TaskDetailModalProps {
+  task: SerializedTask | null;
+  phaseName: string;
+  agentName: string | null;
+  dependencies: DependencyInfo[];
+  dependents: DependencyInfo[];
+  onClose: () => void;
+  onQueueTask: (taskId: string) => void;
+  onStopTask: (taskId: string) => void;
+}
+
+export function TaskDetailModal({
+  task,
+  phaseName,
+  agentName,
+  dependencies,
+  dependents,
+  onClose,
+  onQueueTask,
+  onStopTask,
+}: TaskDetailModalProps) {
+  const allDependenciesComplete =
+    dependencies.length === 0 ||
+    dependencies.every((d) => d.status === "completed");
+
+  const canQueue = task !== null && task.status === "pending" && allDependenciesComplete;
+  const canStop = task !== null && task.status === "in_progress";
+
+  return (
+    <Dialog open={task !== null} onOpenChange={(open) => { if (!open) onClose(); }}>
+      <DialogContent>
+        <DialogHeader>
+          <DialogTitle>{task?.name ?? "Task"}</DialogTitle>
+          <DialogDescription>Task details and dependencies</DialogDescription>
+        </DialogHeader>
+
+        {task && (
+          <div className="space-y-4">
+            {/* Metadata grid */}
+            <div className="grid grid-cols-2 gap-3 text-sm">
+              <div>
+                <span className="text-muted-foreground">Status</span>
+                <div className="mt-1">
+                  <StatusBadge status={task.status} />
+                </div>
+              </div>
+              <div>
+                <span className="text-muted-foreground">Priority</span>
+                <p className="mt-1 font-medium capitalize">{task.priority}</p>
+              </div>
+              <div>
+                <span className="text-muted-foreground">Phase</span>
+                <p className="mt-1 font-medium">{phaseName}</p>
+              </div>
+              <div>
+                <span className="text-muted-foreground">Type</span>
+                <p className="mt-1 font-medium">{task.type}</p>
+              </div>
+              <div className="col-span-2">
+                <span className="text-muted-foreground">Agent</span>
+                <p className="mt-1 font-medium">
+                  {agentName ?? "Unassigned"}
+                </p>
+              </div>
+            </div>
+
+            {/* Description */}
+            <div>
+              <h4 className="mb-1 text-sm font-medium">Description</h4>
+              <p className="text-sm text-muted-foreground">
+                {task.description ?? "No description"}
+              </p>
+            </div>
+
+            {/* Dependencies */}
+            <div>
+              <h4 className="mb-1 text-sm font-medium">Dependencies</h4>
+              {dependencies.length === 0 ? (
+                <p className="text-sm text-muted-foreground">
+                  No dependencies
+                </p>
+              ) : (
+                <ul className="space-y-1">
+                  {dependencies.map((dep) => (
+                    <li
+                      key={dep.name}
+                      className="flex items-center gap-2 text-sm"
+                    >
+                      <span>{dep.name}</span>
+                      <StatusBadge status={dep.status} />
+                    </li>
+                  ))}
+                </ul>
+              )}
+            </div>
+
+            {/* Dependents (Blocks) */}
+            <div>
+              <h4 className="mb-1 text-sm font-medium">Blocks</h4>
+              {dependents.length === 0 ? (
+                <p className="text-sm text-muted-foreground">None</p>
+              ) : (
+                <ul className="space-y-1">
+                  {dependents.map((dep) => (
+                    <li
+                      key={dep.name}
+                      className="flex items-center gap-2 text-sm"
+                    >
+                      <span>{dep.name}</span>
+                      <StatusBadge status={dep.status} />
+                    </li>
+                  ))}
+                </ul>
+              )}
+            </div>
+          </div>
+        )}
+
+        <DialogFooter>
+          <Button
+            variant="outline"
+            size="sm"
+            disabled={!canQueue}
+            onClick={() => task && onQueueTask(task.id)}
+          >
+            Queue Task
+          </Button>
+          <Button
+            variant="destructive"
+            size="sm"
+            disabled={!canStop}
+            onClick={() => task && onStopTask(task.id)}
+          >
+            Stop Task
+          </Button>
+        </DialogFooter>
+      </DialogContent>
+    </Dialog>
+  );
+}