Fixed

• Sidenav: replaced overflow:hidden scroll-lock with position:fixed technique so closing a sidenav no longer scrolls the page back to the top on all browsers (the previous approach was unreliable on iOS Safari and Chrome).
• Task list view: project filter dropdown now persists correctly — a missing change event listener meant selecting a project filter was never saved to localStorage.
• C4 diagram: connections with an empty label can now be saved; the save guard previously required a non-empty label which silently dropped the connection.
• Habits: Cards/Calendar view toggle is now rendered directly in the HTML so it is always visible without relying on JS injection.
• Habits: “Mark done today” button is disabled immediately on click to prevent double-fire before the API response arrives; a guard also skips the call if the habit is already recorded as done today.