feat(dashboard): revenue "year" tile toggles 365 days ↔ calendar YTD

Per request, keep the dashboard to four tiles rather than adding a fifth: the
"Revenue · last 365 days" tile is now clickable and toggles in place between
the trailing-365-day window and calendar year-to-date (since Jan 1).

- adminDashboard: new calendar-year cutoff + revenue.calendarYearMinor (same
  cash-basis paid_at window logic as the existing trio).
- StatCard gains an optional onClick (renders as a button); the year tile uses
  it, with a "Tap to switch window" hint for discoverability.
- bills.service CrmOverviewStats.revenue gains calendarYearMinor.

backend/src/routes/adminDashboard.js

@@ -439,6 +439,10 @@ router.get('/crm-stats', adminAuth, async (req, res) => {
     const monthCutoff   = new Date(now -  30 * DAY);
     const quarterCutoff = new Date(now -  90 * DAY);
     const yearCutoff    = new Date(now - 365 * DAY);
+    // Calendar year-to-date (Jan 1 of the current year, local time) —
+    // the dashboard's revenue "year" tile can toggle between this and
+    // the trailing-365-day window.
+    const calendarYearCutoff = new Date(new Date(now).getFullYear(), 0, 1);
 
     // ---- quotes: counts by status ---------------------------------
     let quoteCounts = { draft: 0, sent: 0, accepted: 0, declined: 0, expired: 0, converted: 0 };
@@ -459,6 +463,7 @@ router.get('/crm-stats', adminAuth, async (req, res) => {
     let revenueMonthMinor = 0;
     let revenueQuarterMinor = 0;
     let revenueYearMinor = 0;
+    let revenueCalendarYearMinor = 0;
     let outstandingTotalMinor = 0;
     let outstandingCount = 0;
 
@@ -507,6 +512,7 @@ router.get('/crm-stats', adminAuth, async (req, res) => {
         revenueMonthMinor        = await winSum(monthCutoff);
         revenueQuarterMinor      = await winSum(quarterCutoff);
         revenueYearMinor         = await winSum(yearCutoff);
+        revenueCalendarYearMinor = await winSum(calendarYearCutoff);
 
         // Outstanding: every invoice that's been sent but not fully
         // paid (sent + overdue). Outstanding = total - paid. We sum
@@ -571,6 +577,7 @@ router.get('/crm-stats', adminAuth, async (req, res) => {
         monthMinor:        revenueMonthMinor,
         quarterMinor:      revenueQuarterMinor,
         yearMinor:         revenueYearMinor,
+        calendarYearMinor: revenueCalendarYearMinor,
       },
       outstanding: {
         totalMinor: outstandingTotalMinor,

frontend/src/components/admin/CrmOverviewSection.tsx

@@ -50,6 +50,10 @@ export const CrmOverviewSection: React.FC = () => {
   // publicSettings finishes loading — shows everything, then settles.
   const showRevenue     = publicSettings?.crm_overview_show_revenue !== false;
   const showOutstanding = publicSettings?.crm_overview_show_outstanding !== false;
+  // Revenue "year" tile toggles in place between the trailing-365-day
+  // window and calendar year-to-date — keeps the dashboard to four
+  // tiles instead of adding a fifth.
+  const [revYearMode, setRevYearMode] = React.useState<'rolling' | 'calendar'>('rolling');
   const showQuotes      = publicSettings?.crm_overview_show_quotes !== false;
   const showInvoices    = publicSettings?.crm_overview_show_invoices !== false;
   // Compute which sub-sections actually render so we can skip the
@@ -121,8 +125,15 @@ export const CrmOverviewSection: React.FC = () => {
               />
               <StatCard
                 icon={<TrendingUp className="w-5 h-5" />}
-                label={t('crmOverview.revenue.year', 'Revenue · last 365 days')}
+                label={revYearMode === 'calendar'
-                value={formatMoney(d.revenue.yearMinor, cur)}
+                  ? t('crmOverview.revenue.yearCalendar', 'Revenue · this year')
+                  : t('crmOverview.revenue.year', 'Revenue · last 365 days')}
+                value={formatMoney(
+                  revYearMode === 'calendar' ? d.revenue.calendarYearMinor : d.revenue.yearMinor,
+                  cur,
+                )}
+                sub={t('crmOverview.revenue.toggleHint', 'Tap to switch window')}
+                onClick={() => setRevYearMode((m) => (m === 'rolling' ? 'calendar' : 'rolling'))}
               />
             </>
           )}
@@ -249,8 +260,11 @@ interface StatCardProps {
   value: string | number;
   sub?: string;
   to?: string;
+  /** Makes the whole tile a button (mutually exclusive with `to`).
+   *  Used by the revenue tile to toggle its window in place. */
+  onClick?: () => void;
 }
-const StatCard: React.FC<StatCardProps> = ({ icon, label, value, sub, to }) => {
+const StatCard: React.FC<StatCardProps> = ({ icon, label, value, sub, to, onClick }) => {
   const inner = (
     <Card padding="md" className="h-full">
       <div className="flex items-start gap-3">
@@ -266,6 +280,13 @@ const StatCard: React.FC<StatCardProps> = ({ icon, label, value, sub, to }) => {
   if (to) {
     return <Link to={to} className="block hover:opacity-90 transition-opacity">{inner}</Link>;
   }
+  if (onClick) {
+    return (
+      <button type="button" onClick={onClick} className="block w-full text-left hover:opacity-90 transition-opacity">
+        {inner}
+      </button>
+    );
+  }
   return inner;
 };
 

frontend/src/services/bills.service.ts

@@ -386,6 +386,9 @@ export interface CrmOverviewStats {
     monthMinor: number;
     quarterMinor: number;
     yearMinor: number;
+    /** Revenue since Jan 1 of the current year (calendar YTD). The
+     *  dashboard's "year" tile toggles between this and yearMinor. */
+    calendarYearMinor: number;
   };
   outstanding: {
     totalMinor: number;