feat(frontend): /?view=inventory route + inventory page scaffold + dark CSS

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/components/inventory/InventorySearchPage.tsx

@@ -0,0 +1,40 @@
+import { useState } from 'react';
+import { useInventorySearch } from './useInventorySearch';
+import { FilterSidebar } from './FilterSidebar';
+import { ActiveChips } from './ActiveChips';
+import { ResultsTable } from './ResultsTable';
+import { DetailPanel } from './DetailPanel';
+import type { InvItem } from './types';
+
+export function InventorySearchPage() {
+  const search = useInventorySearch();
+  const [selected, setSelected] = useState<InvItem | null>(null);
+
+  return (
+    <div className="inv-page">
+      <div className="inv-topbar">
+        <span className="inv-title">⚔ Inventory Search</span>
+        <input
+          className="inv-searchbox"
+          placeholder="Search name or material…"
+          value={search.filters.text}
+          onChange={e => search.update({ text: e.target.value })}
+        />
+        <button className="inv-btn" onClick={() => { search.reset(); setSelected(null); }}>Reset</button>
+        <span className="inv-count">
+          {search.error ? <span className="inv-error">{search.error}</span>
+            : search.result ? <><b>{search.result.total_count.toLocaleString()}</b> items
+                {search.queryMs != null && <> · {search.queryMs} ms</>}
+                {search.loading && ' · …'}</>
+            : 'loading…'}
+        </span>
+      </div>
+      <ActiveChips search={search} />
+      <div className="inv-main">
+        <FilterSidebar search={search} />
+        <ResultsTable search={search} selected={selected} onSelect={setSelected} />
+        {selected && <DetailPanel item={selected} onClose={() => setSelected(null)} />}
+      </div>
+    </div>
+  );
+}