fix(signal-auth): read 'number' field from signal-cli 0.13+ listAccounts

signal-cli >= 0.13 emits the account identifier as `number` in JSON
output, not `account`. The skip-if-already-linked path in signal-auth
always returned an empty list, so re-runs of setup unconditionally
tried `signal-cli link`, which fails when the data directory already
exists.

Read `number` first, fall back to `account` for older signal-cli.

setup/signal-auth.ts

@@ -36,6 +36,7 @@ const LINK_TIMEOUT_MS = 180_000;
 const DEFAULT_DEVICE_NAME = 'NanoClaw';
 
 interface SignalAccount {
+  number?: string;
   account?: string;
   registered?: boolean;
 }
@@ -59,7 +60,7 @@ function listAccounts(): string[] {
     const parsed = JSON.parse(res.stdout || '[]') as SignalAccount[];
     return parsed
       .filter((a) => a.registered !== false)
-      .map((a) => a.account ?? '')
+      .map((a) => a.number ?? a.account ?? '')
       .filter(Boolean);
   } catch {
     return [];