feat(calendar): header continuity with week numbers + skeleton content in fly-rect

- Add ISO week numbers to the left of week rows in month view (8, 9, 10...)
  with spacer alignment on day-of-week headers
- Inject label + skeleton placeholder lines into fly-rect during zoom animations:
  zoom-in shows source label (month name / "Week N" / day name) + pulsing bars
  zoom-out shows target context label + skeleton
- Skeleton CSS uses pulse animation (0.8s alternate) for loading hint
- Non-scoped style block for dynamically injected innerHTML elements
- isoWeekNumber helper for ISO 8601 week calculation
- Extended MonthRow type with weekNumber property

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/app/components/workspace/CrmWorkspaceApp.vue

@@ -2672,6 +2672,14 @@ function weekRowStartForDate(key: string) {
   return dayKey(date);
 }
 
+function isoWeekNumber(dateString: string): number {
+  const d = new Date(`${dateString}T00:00:00`);
+  const t = new Date(d.getTime());
+  t.setDate(t.getDate() + 3 - ((t.getDay() + 6) % 7));
+  const y = new Date(t.getFullYear(), 0, 4);
+  return 1 + Math.round(((t.getTime() - y.getTime()) / 86400000 - 3 + ((y.getDay() + 6) % 7)) / 7);
+}
+
 function nextAnimationFrame() {
   return new Promise<void>((resolve) => {
     requestAnimationFrame(() => resolve());
@@ -2695,6 +2703,48 @@ function resetFlyRectStyle(flyEl: HTMLElement) {
   flyEl.style.backgroundColor = "";
   flyEl.style.borderRadius = "";
   flyEl.style.boxShadow = "";
+  flyEl.innerHTML = "";
+}
+
+function extractSourceLabel(sourceElement: HTMLElement, viewBefore: string): string {
+  if (viewBefore === "year") {
+    const p = sourceElement.querySelector("p");
+    return p?.textContent?.trim() ?? "";
+  }
+  if (viewBefore === "month" || viewBefore === "agenda") {
+    const wn = sourceElement.querySelector(".calendar-week-number");
+    return wn ? `Week ${wn.textContent?.trim()}` : "";
+  }
+  if (viewBefore === "week") {
+    const p = sourceElement.querySelector("p");
+    return p?.textContent?.trim() ?? "";
+  }
+  return "";
+}
+
+function buildFlyRectContent(labelText: string): string {
+  const skeleton = `
+    <div class="calendar-fly-skeleton">
+      <div class="calendar-fly-skeleton-line" style="width:70%"></div>
+      <div class="calendar-fly-skeleton-line" style="width:45%"></div>
+      <div class="calendar-fly-skeleton-line" style="width:60%"></div>
+    </div>
+  `;
+  return `<div class="calendar-fly-content"><p class="calendar-fly-label">${labelText}</p>${skeleton}</div>`;
+}
+
+function buildFlyRectContentForZoomOut(currentView: string): string {
+  let labelText = "";
+  if (currentView === "day") {
+    const d = new Date(`${selectedDateKey.value}T00:00:00`);
+    labelText = new Intl.DateTimeFormat("en-US", { weekday: "short" }).format(d) + " " + d.getDate();
+  } else if (currentView === "week") {
+    const weekStart = weekRowStartForDate(selectedDateKey.value);
+    labelText = `Week ${isoWeekNumber(weekStart)}`;
+  } else if (currentView === "month" || currentView === "agenda") {
+    labelText = new Intl.DateTimeFormat("en-US", { month: "long" }).format(calendarCursor.value);
+  }
+  return buildFlyRectContent(labelText);
 }
 
 async function animateCalendarFlipTransition(
@@ -2740,6 +2790,8 @@ async function animateCalendarFlipTransition(
     flyEl.style.borderColor = "color-mix(in oklab, var(--color-base-300) 100%, transparent)";
     flyEl.style.backgroundColor = "color-mix(in oklab, var(--color-base-100) 100%, transparent)";
     flyEl.style.boxShadow = "";
+    // Inject label + skeleton for zoom-out
+    flyEl.innerHTML = buildFlyRectContentForZoomOut(calendarView.value);
     calendarFlyVisible.value = true;
 
     // 3. Switch to parent view
@@ -2815,18 +2867,22 @@ async function animateCalendarZoomIntoSource(
       return;
     }
 
-    // 1. Fade out siblings
+    // 1. Extract label before fading children
+    const labelText = extractSourceLabel(sourceElement, calendarView.value);
+
+    // 2. Fade out siblings
     const siblings = Array.from(
       sceneEl?.querySelectorAll<HTMLElement>(".calendar-hover-targetable") ?? [],
     ).filter((el) => el !== sourceElement && !sourceElement.contains(el) && !el.contains(sourceElement));
     await calendarTweenTo(siblings, { opacity: 0, duration: CALENDAR_FADE_DURATION, ease: "power2.in" });
 
-    // 2. Fade out source element's inner content (keep border/bg visible)
+    // 3. Fade out source element's inner content (keep border/bg visible)
     const sourceChildren = Array.from(sourceElement.children) as HTMLElement[];
     await calendarTweenTo(sourceChildren, { opacity: 0, duration: 0.12, ease: "power2.in" });
 
-    // 3. Clone source visual style to fly-rect, position at source bounds
+    // 4. Clone source visual style to fly-rect, inject label + skeleton
     cloneElementStyleToFlyRect(sourceElement, flyEl);
+    flyEl.innerHTML = buildFlyRectContent(labelText);
     const srcLeft = sourceRect.left - wrapRect.left;
     const srcTop = sourceRect.top - wrapRect.top;
     gsap.set(flyEl, {
@@ -3067,13 +3123,15 @@ const monthCells = computed(() => {
 });
 
 const monthRows = computed(() => {
-  const rows: Array<{ key: string; startKey: string; cells: typeof monthCells.value }> = [];
+  const rows: Array<{ key: string; startKey: string; weekNumber: number; cells: typeof monthCells.value }> = [];
   for (let index = 0; index < monthCells.value.length; index += 7) {
     const cells = monthCells.value.slice(index, index + 7);
     if (!cells.length) continue;
+    const startKey = cells[0]?.key ?? selectedDateKey.value;
     rows.push({
       key: `${cells[0]?.key ?? index}-week-row`,
-      startKey: cells[0]?.key ?? selectedDateKey.value,
+      startKey,
+      weekNumber: isoWeekNumber(startKey),
       cells,
     });
   }