feat: implement Story 2.2 — Priority Alerts Panel with UI fixes

Add PriorityAlertsPanel component to the dashboard, update DashboardController
with alert logic, and apply misc UI fixes across sidebar, forms, and pages.
Includes epic-1 retrospective and sprint status update.

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

resources/js/components/clients/DeclarationCalendar.vue

@@ -37,14 +37,6 @@ const monthLabel = computed(
         `${monthNames[current.value.getMonth()]} ${current.value.getFullYear()}`,
 );
 
-const datesWithDeclarations = computed(() => {
-    const set = new Set<string>();
-    props.declarations.forEach((f) => {
-        if (f.due_date) set.add(f.due_date);
-    });
-    return set;
-});
-
 const declarationsByDate = computed(() => {
     const map = new Map<string, number>();
     props.declarations.forEach((f) => {