focus: restore body focus on overlay close, test shield, ESC closes results

Focus restoration:
* editor.js closeModal(): blur activeElement after the close so board
  shortcuts (arrows, bare keys) work immediately without clicking.
* detail.js closeDetail(): same blur, skipped when openedFromSearch
  (search input should keep focus in that case).
* search.js closeSearch(): blur after removing .open.
* calendar.js closeCalendar(): blur after closeDayPopup.
All four check activeElement !== body before blurring to avoid no-ops.

Test shield (loader.js):
* ensureProgressBar() now also creates #test-shield — a transparent
  fixed overlay (z-index one below the progress bar) covering the
  viewport below the bar. Blocks all real mouse interaction while
  tests run; synthetic events from the test suite still work because
  they bypass pointer-events. cursor:not-allowed as visual feedback.
  Removed by hideProgress() alongside the progress bar.

ESC closes test results (runner.js):
* The existing keydown listener now also handles Escape when the
  test-panel is visible. stopPropagation prevents the app's Escape
  chain from firing a second close underneath.

Tests (board.test.js):
* New describe "Board: Focus restoration after overlay close":
  - closing the editor returns focus to body
  - closing the detail view returns focus to body
  - closing search returns focus to body
  - arrow keys work after editor round-trip (enter → enter → escape)
    — the exact flow the user reported as broken. Dispatches
    ArrowDown → Enter (detail) → Enter (editor) → Escape (close) →
    asserts body focus → ArrowDown → asserts .card-focused exists.
* Fixed .not.toBe() → (x !== y).toBe(true) since the custom runner
  doesn't have a .not chain.

chore: bump version to 0.9.14

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/js/modules/calendar.js

@@ -506,6 +506,9 @@ export function openCalendar() {
 export function closeCalendar() {
     closeDayPopup();
     overlay.classList.remove('open');
+    if (document.activeElement && document.activeElement !== document.body) {
+        document.activeElement.blur();
+    }
 }
 
 $('calendar-btn')?.addEventListener('click', openCalendar);