Add graceful shutdown (SIGTERM/SIGINT handlers) for clean Docker stop

[pike00]

Summary

The bridge has no signal handlers. When run under Docker, docker stop sends SIGTERM, which Deno ignores by default. After 10 seconds Docker escalates to SIGKILL, killing the process mid-operation. This can corrupt the CouchDB since checkpoint (stored in Deno localStorage), causing the bridge to re-replay or skip changes on restart.

Fix

Add SIGTERM/SIGINT handlers that call Hub.stop(), which awaits all peers' stop() methods (closing file watchers and flushing the localStorage checkpoint). The handler is idempotent via a shuttingDown guard.

Hub.ts — add stop() method

+async stop() {
+    await Promise.all(this.peers.map((p) => p.stop()));
+    this.peers = [];
+}

main.ts — add signal handlers

 const hub = new Hub(config);
 hub.start();
+
+let shuttingDown = false;
+async function shutdown(sig: string) {
+    if (shuttingDown) return;
+    shuttingDown = true;
+    console.log(\`LiveSync Bridge received ${sig}, shutting down...\`);
+    try {
+        await hub.stop();
+    } catch (ex) {
+        console.error(ex);
+    }
+    Deno.exit(0);
+}
+for (const sig of ["SIGTERM", "SIGINT"] as const) {
+    Deno.addSignalListener(sig, () => {
+        void shutdown(sig);
+    });
+}

Impact

Every Docker deployment benefits. Without this, docker stop is effectively a kill -9 after 10 seconds, risking checkpoint corruption on every restart.

[pike00]

I plan on implementing this. I'll submit a PR once it's ready.