Problem

Window/card layout preferences are currently saved only in localStorage under {username}_resourceLayout.
This means:

• Incognito windows — localStorage is cleared on window close, forcing users to rearrange all cards on every
  session.
• Cache clears — any browser cache wipe loses the layout.
• Multiple devices/browsers — layout doesn't sync across them.

This is a significant daily friction point for users who rely on incognito mode to avoid unrelated caching issues.

Proposed Solution

Use the DCS Gitea User Settings API (GET/PATCH /api/v1/user/settings) to persist layout preferences
server-side, tied to the authenticated user account.

Behaviour

1. On login — fetch layout from server and apply it; falls back to localStorage if no server value exists yet.
2. On layout change — debounced (1.5 s) save to server alongside the existing localStorage save.
3. Server unavailable — fails silently, localStorage continues to work as before.

Acceptance Criteria

• Arrange cards in one incognito session, close it, reopen incognito and log in — layout is restored
  automatically.
• Layout changes are saved to GET {server}/api/v1/user/settings within ~2 seconds of last drag/resize.
• No regression when server is offline (graceful localStorage fallback).
• Works on both production (git.door43.org) and QA (qa.door43.org) servers.