feat: Add Line plugin (#1630)

* feat: add LINE plugin (#1630) (thanks @plum-dawg)

* feat: complete LINE plugin (#1630) (thanks @plum-dawg)

* chore: drop line plugin node_modules (#1630) (thanks @plum-dawg)

* test: mock /context report in commands test (#1630) (thanks @plum-dawg)

* test: limit macOS CI workers to avoid OOM (#1630) (thanks @plum-dawg)

* test: reduce macOS CI vitest workers (#1630) (thanks @plum-dawg)

---------

Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/line/probe.ts

@@ -0,0 +1,43 @@
+import { messagingApi } from "@line/bot-sdk";
+import type { LineProbeResult } from "./types.js";
+
+export async function probeLineBot(
+  channelAccessToken: string,
+  timeoutMs = 5000,
+): Promise<LineProbeResult> {
+  if (!channelAccessToken?.trim()) {
+    return { ok: false, error: "Channel access token not configured" };
+  }
+
+  const client = new messagingApi.MessagingApiClient({
+    channelAccessToken: channelAccessToken.trim(),
+  });
+
+  try {
+    const profile = await withTimeout(client.getBotInfo(), timeoutMs);
+
+    return {
+      ok: true,
+      bot: {
+        displayName: profile.displayName,
+        userId: profile.userId,
+        basicId: profile.basicId,
+        pictureUrl: profile.pictureUrl,
+      },
+    };
+  } catch (err) {
+    const message = err instanceof Error ? err.message : String(err);
+    return { ok: false, error: message };
+  }
+}
+
+function withTimeout<T>(promise: Promise<T>, timeoutMs: number): Promise<T> {
+  if (!timeoutMs || timeoutMs <= 0) return promise;
+  let timer: NodeJS.Timeout | null = null;
+  const timeout = new Promise<T>((_, reject) => {
+    timer = setTimeout(() => reject(new Error("timeout")), timeoutMs);
+  });
+  return Promise.race([promise, timeout]).finally(() => {
+    if (timer) clearTimeout(timer);
+  });
+}