feat(wake): long-poll wake listener for instant CLI sync

CLI now holds a GET /api/internal/agent/wake connection open.
When the server calls triggerWake(userId) — on stream request,
download queue, pause, cancel, resume, scan, etc. — the CLI
receives the signal immediately and fires a sync cycle in <100ms
instead of waiting up to 10s for the next scheduled interval.

- Add WaitForWake(ctx) to Client using a no-timeout HTTP client
- Add runWakeListener goroutine to SyncClient (auto-reconnects)
- Start wake listener from SyncClient.Run()

Closes: sub-second stream latency from the web UI

internal/cmd/version.go

@@ -1,4 +1,4 @@
 package cmd
 
 // Version is the CLI version. Overridden by goreleaser ldflags at release time.
-var Version = "0.6.0"
+var Version = "0.6.1"