Add FilterDropdown component and column filter props factory

src/app/table-filters.tsx renders type-specific filter UIs (text search,
category checkbox list, date range) and exposes buildColumnFilterProps to
attach antd controlled filter props (filterDropdown/onFilter/filteredValue)
to a column. Verified against antd v6.4.3 type defs.

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

src/app/table-filters.tsx

@@ -0,0 +1,139 @@
+"use client";
+
+import { Button, Input, Checkbox, DatePicker, Space } from "antd";
+import dayjs from "dayjs";
+import type { ColumnType } from "antd/es/table";
+import type { FilterDropdownProps } from "antd/es/table/interface";
+import { inferFilterType, distinctValues, matchesFilter } from "./table-filters";
+import type { DataRow, FilterType } from "./table-filters";
+
+const DATE_FMT = "YYYY-MM-DD";
+
+/** 解析受控 selectedKeys 里的 "start|end" 编码为 RangePicker 值。 */
+function decodeRange(keys: React.Key[]): [dayjs.Dayjs | null, dayjs.Dayjs | null] {
+  const raw = keys[0] != null ? String(keys[0]) : "";
+  const sep = raw.indexOf("|");
+  if (sep < 0) return [null, null];
+  const s = raw.slice(0, sep);
+  const e = raw.slice(sep + 1);
+  return [s ? dayjs(s, DATE_FMT) : null, e ? dayjs(e, DATE_FMT) : null];
+}
+
+export function FilterDropdown({
+  type,
+  distinct,
+  setSelectedKeys,
+  selectedKeys,
+  confirm,
+  clearFilters,
+}: FilterDropdownProps & {
+  type: FilterType;
+  distinct: string[];
+}): React.ReactElement {
+  if (type === "date") {
+    const [start, end] = decodeRange(selectedKeys);
+    return (
+      <div style={{ padding: 8 }}>
+        <DatePicker.RangePicker
+          value={[start, end]}
+          onChange={(dates) => {
+            if (!dates || dates[0] == null || dates[1] == null) {
+              setSelectedKeys([]);
+            } else {
+              const s = dates[0].format(DATE_FMT);
+              const e = dates[1].format(DATE_FMT);
+              setSelectedKeys([`${s}|${e}`]); // 单个编码键，供 onFilter 解码
+            }
+          }}
+        />
+        <Space style={{ marginTop: 8, display: "flex", justifyContent: "flex-end" }}>
+          <Button
+            size="small"
+            onClick={() => {
+              clearFilters?.();
+              confirm();
+            }}
+          >
+            重置
+          </Button>
+          <Button type="primary" size="small" onClick={() => confirm()}>
+            确定
+          </Button>
+        </Space>
+      </div>
+    );
+  }
+
+  if (type === "category") {
+    return (
+      <div style={{ padding: 8, maxWidth: 260 }}>
+        <Checkbox.Group
+          style={{ display: "flex", flexDirection: "column", maxHeight: 240, overflow: "auto" }}
+          value={(selectedKeys as string[]) ?? []}
+          onChange={(vals) => setSelectedKeys(vals as React.Key[])}
+          options={distinct}
+        />
+        <Space style={{ marginTop: 8, display: "flex", justifyContent: "flex-end" }}>
+          <Button
+            size="small"
+            onClick={() => {
+              clearFilters?.();
+              confirm();
+            }}
+          >
+            重置
+          </Button>
+          <Button type="primary" size="small" onClick={() => confirm()}>
+            确定
+          </Button>
+        </Space>
+      </div>
+    );
+  }
+
+  // text
+  const textValue = selectedKeys[0] != null ? String(selectedKeys[0]) : "";
+  return (
+    <div style={{ padding: 8 }}>
+      <Input
+        placeholder="输入关键字"
+        value={textValue}
+        onChange={(e) => setSelectedKeys(e.target.value ? [e.target.value] : [])}
+        onPressEnter={() => confirm()}
+        style={{ marginBottom: 8, display: "block" }}
+        allowClear
+      />
+      <Space style={{ display: "flex", justifyContent: "flex-end" }}>
+        <Button
+          size="small"
+          onClick={() => {
+            clearFilters?.();
+            confirm();
+          }}
+        >
+          重置
+        </Button>
+        <Button type="primary" size="small" onClick={() => confirm()}>
+          确定
+        </Button>
+      </Space>
+    </div>
+  );
+}
+
+/** 为某列构造 antd 受控筛选属性（filterDropdown / onFilter / filteredValue）。 */
+export function buildColumnFilterProps(
+  key: string,
+  data: DataRow[],
+  filteredValue: React.Key[] | null
+): Partial<ColumnType<DataRow>> {
+  const type = inferFilterType(key, data);
+  const distinct = type === "category" ? distinctValues(key, data) : [];
+  return {
+    filterDropdown: (props) => (
+      <FilterDropdown type={type} distinct={distinct} {...props} />
+    ),
+    onFilter: (value, record) => matchesFilter(type, record[key], String(value)),
+    filteredValue: filteredValue ?? null,
+  };
+}