feat(filters): smart query bar with amount operators and multi-select dropdowns

- Query bar parses >500, >=500, <500, <=500, 500-1500 into amount_min/max filters
- Parsed tokens shown as dismissable chips below the query bar
- Category, Bank, Tag, Type filters upgraded from single-select to multi-select
- MultiSelect dropdown component with checkbox list and active-state border
- Backend: TransactionFilters uses string[] for categories/bank_names/tag_ids/transaction_types
- SQL: ANY($n::text[]) / ANY($n::int[]) for array filters

src/app/api/transactions/route.ts

@@ -8,18 +8,22 @@ export async function GET(req: NextRequest) {
   if (!user) return NextResponse.json({ error: "Unauthorized" }, { status: 403 });
 
   const sp = req.nextUrl.searchParams;
+  const parseArr = (key: string) => { const v = sp.get(key); return v ? v.split(",").filter(Boolean) : undefined; };
   const result = await getTransactions(user.id, {
     from: sp.get("from") || undefined,
     to: sp.get("to") || undefined,
-    category: sp.get("category") || undefined,
-    bank_name: sp.get("bank_name") || undefined,
+    categories: parseArr("categories"),
+    bank_names: parseArr("bank_names"),
+    tag_ids: parseArr("tag_ids"),
+    transaction_types: parseArr("transaction_types"),
     search: sp.get("search") || undefined,
     statement_id: sp.get("statement_id") || undefined,
-    tag_id: sp.get("tag_id") || undefined,
     sort_by: sp.get("sort_by") || undefined,
     sort_dir: sp.get("sort_dir") || undefined,
     limit: sp.get("limit") ? Number(sp.get("limit")) : undefined,
     offset: sp.get("offset") ? Number(sp.get("offset")) : undefined,
+    amount_min: sp.get("amount_min") ? Number(sp.get("amount_min")) : undefined,
+    amount_max: sp.get("amount_max") ? Number(sp.get("amount_max")) : undefined,
   });
 
   return NextResponse.json(result);