fix(hook): suppress peer list when daemon is unreachable

Fold daemonError into SessionAnnounceOptions so the helper owns the
mutually-exclusive choice between peer list and daemon-down hint. Before
this fix, a session-announce against an unreachable daemon emitted both
"No other mailboxes seen within the last 60 minutes (0 total registered)."
(misleading — the daemon was never asked) AND the daemon-unreachable hint.
Now only the hint appears when the daemon is down.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

node/tests/hook.test.ts

@@ -402,6 +402,20 @@ describe("buildSessionAnnounceLines", () => {
     expect(out).not.toContain("watch --block");
     expect(out).not.toContain("run_in_background");
   });
+
+  it("replaces the peer list with the daemonError hint when daemon is unreachable", () => {
+    const out = buildSessionAnnounceLines({
+      name: "alice-abc12345",
+      peers: [],
+      windowMinutes: 60,
+      maxPeers: 10,
+      daemonError: "[Claude-Mailbox] Daemon not reachable at http://127.0.0.1:1.",
+    }).join("\n");
+    expect(out).toContain("Daemon not reachable");
+    // The misleading "no peers" line must NOT appear when the daemon is down.
+    expect(out).not.toMatch(/No other mailboxes seen/);
+    expect(out).not.toMatch(/Active peers/);
+  });
 });
 
 describe("readSettings / writeSettings roundtrip", () => {