Build a polished, responsive task management web app called "Focus Desk" in this empty directory.
Use vanilla HTML, CSS and JavaScript, no frameworks, no external dependencies, fonts, CDNs or network services. Entry point: index.html, served with python3 -m http.server. Work only in your current project directory. Do not delegate, use external tools/services, or inspect sibling directories. Finish autonomously without questions.

Requirements:
1. Create tasks with a required non-whitespace title, optional notes, priority (low/medium/high), optional due date. Provide task editing, deletion, and reversible complete/incomplete toggle.
2. Search titles AND notes case-insensitively; filter all/active/completed and by priority. Filters and search must combine correctly. Show a useful empty-result state.
3. Persist all tasks and changes in localStorage across reloads. Initial state is empty; never reseed demo tasks. Display total/active/completed task counts. Handle invalid saved JSON gracefully.
4. A thoughtful, beautiful productivity interface, with strong typography, spacing, clear hierarchy, visible keyboard focus, accessible labels, semantic buttons, and responsive layout at 390px and 1440px. No horizontal overflow. Light theme, restrained indigo accent. English UI is fine.
5. Include a concise README explaining running and manual verification. Verify the implementation using locally available commands before finishing. Do not start a persistent server. Do not install packages. Do not create artificial delays.

For reliable black-box verification, use these data-testid attributes on real user-facing elements:
task-title (creation input), task-notes (creation field), task-priority (native select with values low/medium/high), task-due (date input), add-task (submit button), search (search input), status-filter (native select values all/active/completed), priority-filter (native select values all/low/medium/high), task-list (task container), task-item (each task), task-toggle (checkbox within each task), task-edit (button within each task), task-delete (button within each task), edit-title (editing title input), save-edit (save button), empty-state (visible when no matching tasks), count-total/count-active/count-completed (each contains only its numeric count).
Keep the creation form directly visible. Task text must be rendered safely as text (no HTML injection). Editing must allow changing the title at minimum, ideally all fields. Produce complete runnable code and then briefly summarize what you implemented and checked.

Budget-conscious implementation constraint for this trial: keep all source code under 24 KB total, avoid verbose decorative SVGs, and use index.html, style.css, app.js, README.md. Aim to complete in at most 10 model turns. Spend the effort on working features, clear layout and correctness. No long planning or final essay.