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/AttendanceHistory.tsx

@@ -29,7 +29,6 @@ import {
   Button,
   Card,
   DataTable,
-  Field,
   FilterBar,
   MonthField,
   ProgressBar,
@@ -515,10 +514,8 @@ export default function AttendanceHistory() {
 
       {/* Filters */}
       <FilterBar>
-        <Box sx={{ flex: "1 1 200px" }}>
-          <Field label="Měsíc">
-            <MonthField value={month} onChange={(val) => setMonth(val)} />
-          </Field>
+        <Box sx={{ flex: "0 0 180px" }}>
+          <MonthField value={month} onChange={(val) => setMonth(val)} />
         </Box>
       </FilterBar>