p4(ui): Plugin Marketplace skeleton component

api/admin_ui/src/components/PluginMarketplace.tsx

@@ -0,0 +1,50 @@
+import React, { useState } from 'react';
+import { Box, Typography, TextField, InputAdornment, Grid, Card, CardContent } from '@mui/material';
+import SearchIcon from '@mui/icons-material/Search';
+
+/**
+ * Minimal placeholder for the Admin Console Plugin Marketplace.
+ * - Strict TypeScript compliant (no unused vars)
+ * - Not wired into the App shell yet; safe to compile
+ * - No provider name checks; trait‑gated wiring will come in later PRs
+ */
+export default function PluginMarketplace(): JSX.Element {
+  const [query, setQuery] = useState('');
+
+  return (
+    <Box sx={{ px: { xs: 1, sm: 2, md: 3 }, py: 2 }}>
+      <Typography variant="h4" sx={{ mb: 2 }}>
+        Plugin Marketplace
+      </Typography>
+
+      <TextField
+        fullWidth
+        placeholder="Search plugins…"
+        value={query}
+        onChange={(e) => setQuery(e.target.value)}
+        InputProps={{
+          startAdornment: (
+            <InputAdornment position="start">
+              <SearchIcon />
+            </InputAdornment>
+          ),
+        }}
+        sx={{ mb: 3 }}
+      />
+
+      <Grid container spacing={2}>
+        {/* Empty state placeholder; results will be populated in later PRs */}
+        <Grid item xs={12}>
+          <Card variant="outlined">
+            <CardContent>
+              <Typography color="text.secondary">
+                Marketplace results will appear here. Use traits to gate provider‑specific UI.
+              </Typography>
+            </CardContent>
+          </Card>
+        </Grid>
+      </Grid>
+    </Box>
+  );
+}
+