feat: split text and voice channel selection

Separate text moderation and voice recording guild/channel state so each workflow can persist and operate independently.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/routes/syncRoutes.test.ts

@@ -0,0 +1,47 @@
+import type { Request, Response } from "express";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { createSyncRoutes } from "../../src/routes/syncRoutes";
+
+const syncSelectedChannelBacklog = vi.hoisted(() => vi.fn());
+
+vi.mock("../../src/moderation/backlogSync", () => ({
+  syncSelectedChannelBacklog,
+}));
+
+describe("createSyncRoutes", () => {
+  beforeEach(() => {
+    syncSelectedChannelBacklog.mockReset();
+  });
+
+  it("syncs the selected guild and channel from the request", async () => {
+    syncSelectedChannelBacklog.mockResolvedValue(3);
+    const router = createSyncRoutes({} as never);
+    const route = router.stack.find(
+      (layer) => layer.route?.path === "/backlog-sync",
+    );
+    const handler = route?.route?.stack[0]?.handle;
+
+    const json = vi.fn();
+    const next = vi.fn();
+
+    await handler?.(
+      {
+        body: { guildId: "selected-guild", channelId: "selected-channel" },
+      } as Request,
+      { json } as unknown as Response,
+      next,
+    );
+
+    expect(syncSelectedChannelBacklog).toHaveBeenCalledWith(
+      {},
+      "selected-guild",
+      "selected-channel",
+    );
+    expect(json).toHaveBeenCalledWith({
+      success: true,
+      channelId: "selected-channel",
+      messagesSync: 3,
+    });
+    expect(next).not.toHaveBeenCalled();
+  });
+});