fix(ui): unify list filters across all pages (bare controls, standard sizes)

Every list-page FilterBar now follows one spec: bare controls (no Field label rows — which broke flex-end alignment), standardized widths (search 1 1 320px grows; small selects 0 0 160px; entity selects 0 0 220px; MonthField 0 0 180px; dates 0 0 150px), consistent 'Všechny/Všichni/Všechna <entity>' defaults, and a placeholder on every search. TripsAdmin's separate month-Select + year-Select collapse into one MonthField (yyyy-MM, split at the query boundary) — matching Attendance/TripsHistory. The 4 labeled attendance/trips pages move off the Field wrapper; Projects & ReceivedInvoices move their inline search into a FilterBar. Chrome-verified all ~18 filter pages in light + the existing theme.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/pages/ReceivedInvoices.tsx

@@ -30,6 +30,7 @@ import {
   Modal,
   ConfirmDialog,
   Field,
+  FilterBar,
   TextField,
   Select,
   DateField,
@@ -762,14 +763,16 @@ export default function ReceivedInvoices({
         transition={{ duration: 0.25, delay: 0.08 }}
       >
         <Card>
-          <Box sx={{ mb: 2 }}>
-            <TextField
-              value={search}
-              onChange={(e) => setSearch(e.target.value)}
-              placeholder="Hledat podle dodavatele nebo čísla faktury..."
-              fullWidth
-            />
-          </Box>
+          <FilterBar>
+            <Box sx={{ flex: "1 1 320px" }}>
+              <TextField
+                value={search}
+                onChange={(e) => setSearch(e.target.value)}
+                placeholder="Hledat podle dodavatele nebo čísla faktury..."
+                fullWidth
+              />
+            </Box>
+          </FilterBar>
 
           {showListSkeleton ? (
             <LoadingState />