feat(feishu): add Feishu inbound webhook, /gh commands and card actions

- add feishu_links D1 table and link store helpers
- implement X-Lark-Signature verification, url_verification, /gh login|logout|comment|merge|close and card.action.trigger Merge/Close
- render interactive cards with clickable title link, inline links and callback buttons (no whole-card card_link)
- bind Feishu account in OAuth callback
- document event subscription and required scopes

server/routes/feishu/webhook.post.ts

@@ -0,0 +1,14 @@
+import { readRawBody } from "h3";
+import { handleFeishuWebhookRequest } from "../../lib/drivers/feishu/updates";
+import { cfEnv, rawRequest } from "../../lib/cf";
+
+export default defineEventHandler(async (event) => {
+  const source = rawRequest(event);
+  const body = await readRawBody(event, "utf8");
+  const request = new Request(source.url, {
+    method: source.method,
+    headers: source.headers,
+    body,
+  });
+  return handleFeishuWebhookRequest(request, cfEnv(event));
+});