fix: resolve task state inconsistency with rapid user actions

[iamsuiux]

Fix: Task State Inconsistency Bug

Problem: Tasks were randomly disappearing/reverting when users performed rapid actions (mark complete + add new task quickly).

Root Cause: Race conditions in state management - functions were using stale state instead of current state.

Solution:

• Replaced direct state access with functional updates (setTasks(prevTasks => ...))

Files Changed: src/hooks/useTasks.ts

Result: Tasks now maintain consistent state during rapid user interactions. No more disappearing/duplicate tasks.