refactor: unify channel config matching and gating

Co-authored-by: thewilloftheshadow <thewilloftheshadow@users.noreply.github.com>

src/slack/monitor/channel-config.test.ts

@@ -42,4 +42,16 @@ describe("resolveSlackChannelConfig", () => {
       matchSource: "wildcard",
     });
   });
+
+  it("uses direct match metadata when channel config exists", () => {
+    const res = resolveSlackChannelConfig({
+      channelId: "C1",
+      channels: { C1: { allow: true, requireMention: false } },
+      defaultRequireMention: true,
+    });
+    expect(res).toMatchObject({
+      matchKey: "C1",
+      matchSource: "direct",
+    });
+  });
 });