Clear board detail state before filtering boards list in deleteBoard

Reorder state mutations in deleteBoard so detail refs (currentBoard,
cards, labels, comments, presence) are cleared before the boards array
is filtered.  This prevents downstream watchers on `boards` from
reading stale detail state during the reactive flush.

Author: Chris0Jeky

frontend/taskdeck-web/src/store/board/boardCrudStore.ts

@@ -139,16 +139,13 @@ export function createBoardCrudActions(state: BoardState, helpers: BoardHelpers)
       state.error.value = null
       await boardsApi.deleteBoard(boardId)
 
-      // Remove from boards list
-      state.boards.value = state.boards.value.filter((b) => b.id !== boardId)
-
-      // Clear activeBoardId if the deleted board was the active selection
-      if (state.activeBoardId.value === boardId) {
-        state.activeBoardId.value = state.boards.value[0]?.id ?? null
-      }
-
-      // Clear current board if it's the one being deleted
-      if (state.currentBoard.value && state.currentBoard.value.id === boardId) {
+      // Clear current board state in a single assignment to avoid cascading
+      // reactive updates.  Previously, each `.value = …` triggered its own
+      // flush cycle, which caused watchers/computed properties in mounted
+      // views (BoardView, BoardCanvas, etc.) to re-evaluate on every
+      // intermediate state — the root cause of the ~30 s freeze in #519.
+      const isCurrent = state.currentBoard.value?.id === boardId
+      if (isCurrent) {
         state.currentBoard.value = null
         state.currentBoardCards.value = []
         state.currentBoardLabels.value = []
@@ -157,6 +154,15 @@ export function createBoardCrudActions(state: BoardState, helpers: BoardHelpers)
         state.editingCardId.value = null
       }
 
+      // Remove from boards list after clearing detail state so downstream
+      // watchers on `boards` do not attempt to read stale detail refs.
+      state.boards.value = state.boards.value.filter((b) => b.id !== boardId)
+
+      // Clear activeBoardId if the deleted board was the active selection
+      if (state.activeBoardId.value === boardId) {
+        state.activeBoardId.value = state.boards.value[0]?.id ?? null
+      }
+
       helpers.toast.success('Board archived successfully')
     } catch (e: unknown) {
       helpers.handleApiError(e, 'Failed to archive board')