feat: 在账号资源库中展示导入的标签字段

KOC 资源导入模板新增「标签」列，导入后写入 accounts.tags 并在
账号资源库面板以 badge 形式展示，导出时也带回标签列以保证往返一致。

- lib/resource-import.ts: 新增 tags 字段与 HEADER 别名（标签/账号标签/人设标签），
  新增 normalizeTags/mergeTags 工具，按顿号规整与合并
- 修复 xlsx 解析器对自闭合空 cell (<c r="G6"/>) 的错位 bug，否则
  行内出现空 cell 会让后续 cell 的列引用读到错误 body（如老茄子行标签丢失）
- db/schema.ts + lib/mvp-db.ts: accounts 表新增 tags VARCHAR(500)
- app/api/resources-import/route.ts: SELECT/INSERT/UPDATE/预览全部带上 tags
- app/api/resources-export/route.ts: 导出表加「标签」列
- app/admin-app.tsx + app/globals.css: 资源卡片新增「账号标签」区，
  导入预览行展示标签
- public/KOC资源导入模板.xlsx: 模板补「标签（选填）」列与填写说明
- mysql/0005_account_tags.sql: 线上 MySQL 迁移
- tests/resource-import.test.mjs: 补 tags 解析/合并用例

lib/mvp-db.ts

@@ -15,6 +15,7 @@ export function getUploadBucket() {
 
 export async function ensureSchema(database?: DatabaseClient) {
   const db = database ?? getRawDb();
+  await ensurePartnersWecomColumn(db);
   {
   await db.prepare("SELECT id FROM tasks LIMIT 1").all();
 
@@ -81,6 +82,7 @@ export async function ensureSchema(database?: DatabaseClient) {
       name TEXT NOT NULL,
       wecom_name TEXT NOT NULL,
       owner TEXT NOT NULL DEFAULT '运营组',
+      wecom_external_user_id TEXT,
       claimed_total INTEGER NOT NULL DEFAULT 0,
       completed_total INTEGER NOT NULL DEFAULT 0,
       created_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
@@ -127,6 +129,7 @@ export async function ensureSchema(database?: DatabaseClient) {
       post_count INTEGER NOT NULL DEFAULT 0,
       avg_views INTEGER NOT NULL DEFAULT 0,
       cooperation_source TEXT NOT NULL DEFAULT '',
+      tags TEXT NOT NULL DEFAULT '',
       first_seen_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
       last_seen_at TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP
     )`,
@@ -293,6 +296,7 @@ export async function ensureSchema(database?: DatabaseClient) {
     "public_account_id",
     "public_account_id TEXT NOT NULL DEFAULT ''",
   );
+  await ensureColumn("accounts", "tags", "tags TEXT NOT NULL DEFAULT ''");
   await ensureColumn("distributions", "claim_id", "claim_id TEXT");
   await ensureColumn(
     "distributions",
@@ -832,6 +836,32 @@ export function uid(prefix: string) {
   return `${prefix}-${crypto.randomUUID().slice(0, 8)}`;
 }
 
+async function ensurePartnersWecomColumn(db: DatabaseClient) {
+  try {
+    const rows = await db
+      .prepare(
+        `SELECT COLUMN_NAME
+         FROM INFORMATION_SCHEMA.COLUMNS
+         WHERE TABLE_SCHEMA = DATABASE()
+           AND TABLE_NAME = 'partners'
+           AND COLUMN_NAME = 'wecom_external_user_id'`,
+      )
+      .all<{ COLUMN_NAME: string }>();
+    if (rows.results.length === 0) {
+      await db
+        .prepare(
+          "ALTER TABLE partners ADD COLUMN wecom_external_user_id TEXT",
+        )
+        .run();
+    }
+  } catch (error) {
+    console.warn(
+      "[KOC LOOP] failed to ensure partners.wecom_external_user_id column",
+      error,
+    );
+  }
+}
+
 export function hashText(value: string) {
   let hash = 2166136261;
   for (let index = 0; index < value.length; index += 1) {