fix: address code review findings - data loss, race condition, broken features

- TopBar: call closeBoard() before navigating back to prevent data loss
- board-store: guard debouncedSave against race condition when board is
  closed during an in-flight save
- board-store: add missing updatedAt to setColumnWidth
- useKeyboardShortcuts: remove duplicate Ctrl+K handler that prevented
  command palette from toggling closed
- AttachmentSection: wire up Tauri file dialog for adding attachments
  with link/copy mode support

src/components/card-detail/AttachmentSection.tsx

@@ -1,6 +1,8 @@
 import { FileIcon, X, Plus } from "lucide-react";
+import { open } from "@tauri-apps/plugin-dialog";
 import { Button } from "@/components/ui/button";
 import { useBoardStore } from "@/stores/board-store";
+import { copyAttachment } from "@/lib/storage";
 import type { Attachment } from "@/types/board";
 
 interface AttachmentSectionProps {
@@ -12,11 +14,29 @@ export function AttachmentSection({
   cardId,
   attachments,
 }: AttachmentSectionProps) {
+  const addAttachment = useBoardStore((s) => s.addAttachment);
   const removeAttachment = useBoardStore((s) => s.removeAttachment);
 
-  function handleAdd() {
-    // Placeholder: Tauri file dialog will be wired in a later task
-    console.log("Add attachment (file dialog not yet wired)");
+  async function handleAdd() {
+    const selected = await open({
+      multiple: false,
+      title: "Select attachment",
+    });
+    if (!selected) return;
+
+    const fileName = selected.split(/[\\/]/).pop() ?? "attachment";
+
+    const board = useBoardStore.getState().board;
+    if (!board) return;
+
+    const mode = board.settings.attachmentMode;
+
+    if (mode === "copy") {
+      const destPath = await copyAttachment(board.id, selected, fileName);
+      addAttachment(cardId, { name: fileName, path: destPath, mode: "copy" });
+    } else {
+      addAttachment(cardId, { name: fileName, path: selected, mode: "link" });
+    }
   }
 
   return (

src/components/layout/TopBar.tsx

@@ -75,7 +75,10 @@ export function TopBar() {
               <Button
                 variant="ghost"
                 size="sm"
-                onClick={() => setView({ type: "board-list" })}
+                onClick={() => {
+                  useBoardStore.getState().closeBoard();
+                  setView({ type: "board-list" });
+                }}
                 className="text-pylon-text-secondary hover:text-pylon-text"
               >
                 <ArrowLeft className="size-4" />

src/hooks/useKeyboardShortcuts.ts

@@ -17,14 +17,8 @@ export function useKeyboardShortcuts(): void {
     function handleKeyDown(e: KeyboardEvent) {
       const ctrl = e.ctrlKey || e.metaKey;
 
-      // Ctrl+K: open command palette (always works, even in inputs)
-      if (ctrl && e.key === "k") {
-        e.preventDefault();
-        document.dispatchEvent(new CustomEvent("open-command-palette"));
-        return;
-      }
-
       // Skip remaining shortcuts when an input is focused
+      // Note: Ctrl+K for command palette is handled directly by CommandPalette component
       if (isInputFocused()) return;
 
       // Ctrl+Shift+Z: redo

src/stores/board-store.ts

@@ -63,6 +63,7 @@ function now(): string {
 
 function debouncedSave(
   board: Board,
+  get: () => BoardState & BoardActions,
   set: (partial: Partial<BoardState>) => void
 ): void {
   if (saveTimeout) clearTimeout(saveTimeout);
@@ -70,10 +71,15 @@ function debouncedSave(
     set({ saving: true });
     try {
       await saveBoard(board);
+      // Only update state if the same board is still loaded
+      if (get().board?.id === board.id) {
         set({ saving: false, lastSaved: Date.now() });
+      }
     } catch {
+      if (get().board?.id === board.id) {
         set({ saving: false });
       }
+    }
   }, 500);
 }
 
@@ -86,7 +92,7 @@ function mutate(
   if (!board) return;
   const updated = updater(board);
   set({ board: updated });
-  debouncedSave(updated, set);
+  debouncedSave(updated, get, set);
 }
 
 export const useBoardStore = create<BoardState & BoardActions>()(
@@ -166,6 +172,7 @@ export const useBoardStore = create<BoardState & BoardActions>()(
       setColumnWidth: (columnId, width) => {
         mutate(get, set, (b) => ({
           ...b,
+          updatedAt: now(),
           columns: b.columns.map((c) =>
             c.id === columnId ? { ...c, width } : c
           ),