feat: implement Havenllo single-board kanban (Go+SQLite backend, Preact/Vite frontend)

- Single fixed 'Haven' board: lists (To do/In progress/Done) + cards, no multi-board
- Go 1.24 backend, CGO-free modernc.org/sqlite, embedded SPA, REST /api
- Preact + Vite + TS frontend, native HTML5 drag-and-drop, optimistic UI, dark Haven theme
- PVC (nfs-client) for SQLite, root container on NFS, simple nginx ingress havenllo.haven
- Dockerfile multi-arch build, Gitea CI via pipeline-actions@main

web/src/components/CardItem.tsx

@@ -0,0 +1,113 @@
+import { useState } from "preact/hooks";
+import { beginCardDrag } from "../drag";
+import type { Card } from "../types";
+import { CardEditor } from "./CardEditor";
+import { ConfirmDialog } from "./ConfirmDialog";
+
+interface CardItemProps {
+  card: Card;
+  onEdit: (patch: { title?: string; description?: string; done?: boolean }) => Promise<void>;
+  onDelete: () => Promise<void>;
+}
+
+export function CardItem({ card, onEdit, onDelete }: CardItemProps) {
+  const [editingTitle, setEditingTitle] = useState(false);
+  const [title, setTitle] = useState(card.title);
+  const [expanded, setExpanded] = useState(false);
+  const [confirming, setConfirming] = useState(false);
+  const [saving, setSaving] = useState(false);
+
+  const saveTitle = async () => {
+    if (!title.trim()) return;
+    setSaving(true);
+    try {
+      await onEdit({ title });
+      setEditingTitle(false);
+    } catch {
+      setTitle(card.title);
+    } finally {
+      setSaving(false);
+    }
+  };
+
+  const remove = async () => {
+    setConfirming(false);
+    try {
+      await onDelete();
+    } catch {
+      // The global mutation handler reports the failure.
+    }
+  };
+
+  return (
+    <>
+      <article
+        class={"card " + (card.done ? "card-done" : "")}
+        draggable={!editingTitle}
+        onDragStart={(event) => beginCardDrag(event as unknown as DragEvent, card)}
+      >
+        <div class="card-topline">
+          <button
+            type="button"
+            class={"done-button " + (card.done ? "is-done" : "")}
+            aria-label={card.done ? "Mark card active" : "Mark card done"}
+            title={card.done ? "Mark active" : "Mark done"}
+            disabled={saving}
+            onClick={() => void onEdit({ done: !card.done })}
+          >
+            {card.done ? "✓" : ""}
+          </button>
+          <div class="card-title-wrap">
+            {editingTitle ? (
+              <input
+                class="card-title-input"
+                value={title}
+                maxlength={240}
+                aria-label="Card title"
+                autoFocus
+                onInput={(event) => setTitle(event.currentTarget.value)}
+                onKeyDown={(event) => {
+                  if (event.key === "Enter") void saveTitle();
+                  if (event.key === "Escape") {
+                    setTitle(card.title);
+                    setEditingTitle(false);
+                  }
+                }}
+                onBlur={() => void saveTitle()}
+              />
+            ) : (
+              <button type="button" class="card-title" onClick={() => setEditingTitle(true)}>{card.title}</button>
+            )}
+          </div>
+          <button
+            type="button"
+            class="card-menu"
+            title="Open card details"
+            aria-label="Open card details"
+            onClick={() => setExpanded((value) => !value)}
+          >
+            •••
+          </button>
+        </div>
+        {card.description && !expanded ? <p class="card-preview">{card.description}</p> : null}
+        {expanded ? (
+          <CardEditor
+            card={card}
+            onSave={(description) => onEdit({ description })}
+            onClose={() => setExpanded(false)}
+            onDelete={() => setConfirming(true)}
+          />
+        ) : null}
+      </article>
+      <ConfirmDialog
+        open={confirming}
+        title="Delete this card?"
+        detail={"“" + card.title + "” will be permanently removed."}
+        confirmLabel="Delete card"
+        onCancel={() => setConfirming(false)}
+        onConfirm={() => void remove()}
+      />
+    </>
+  );
+}
+