feat(calendar): click due-date day to navigate to filtered Reporting view

- CalendarWidget accepts onDateClick prop; due-date cells are clickable
  with pointer cursor, red hover highlight, and updated tooltip
- App.js wires onDateClick: sets calendarFilter state and navigates to
  the Reporting page
- NavDrawer navigation to Reporting clears calendarFilter so it only
  applies on calendar-initiated navigation
- ReportingPage accepts filterDate prop; initializes columnFilters with
  { dueDate: Set([filterDate]) } so the view lands pre-filtered
- Existing Clear Filters button lets the user dismiss the filter normally

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

frontend/src/components/pages/ReportingPage.js

@@ -564,7 +564,7 @@ function TableCell({ colKey, finding }) {
 // ---------------------------------------------------------------------------
 // Main ReportingPage
 // ---------------------------------------------------------------------------
-export default function ReportingPage() {
+export default function ReportingPage({ filterDate }) {
     const [findings, setFindings]         = useState([]);
     const [total, setTotal]               = useState(null);
     const [syncedAt, setSyncedAt]         = useState(null);
@@ -574,7 +574,9 @@ export default function ReportingPage() {
     const [syncing, setSyncing]           = useState(false);
     const [sort, setSort]                 = useState({ field: 'severity', dir: 'desc' });
     const [columnOrder, setColumnOrder]   = useState(loadColumnOrder);
-    const [columnFilters, setColumnFilters] = useState({});
+    const [columnFilters, setColumnFilters] = useState(() =>
+        filterDate ? { dueDate: new Set([filterDate]) } : {}
+    );
     const [openFilter, setOpenFilter]     = useState(null);
     const filterBtnRefs                   = useRef({});