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/lib/hooks.ts

@@ -14,21 +14,29 @@ interface TransactionsResponse {
 interface TransactionFilters {
   from?: string;
   to?: string;
-  category?: string;
-  bank_name?: string;
+  categories?: string[];
+  bank_names?: string[];
+  tag_ids?: string[];
+  transaction_types?: string[];
   search?: string;
   statement_id?: string;
-  tag_id?: string;
   sort_by?: string;
   sort_dir?: string;
   limit?: number;
   offset?: number;
+  amount_min?: number;
+  amount_max?: number;
 }
 
 function buildParams(filters: TransactionFilters): string {
   const params = new URLSearchParams();
   Object.entries(filters).forEach(([key, val]) => {
-    if (val !== undefined && val !== "") params.set(key, String(val));
+    if (val === undefined || val === "") return;
+    if (Array.isArray(val)) {
+      if (val.length > 0) params.set(key, val.join(","));
+    } else {
+      params.set(key, String(val));
+    }
   });
   return params.toString();
 }