feat: Add SSE streaming for instant page load and real-time updates

New refresh_mode 'stream' eliminates blocking database queries from initial
page load. Page renders instantly with skeleton UI, then hydrates via SSE.

- Add SSE hub for managing client connections and broadcasting
- Add /api/stream endpoint with init and update events
- Add stream.html skeleton template with loading animations
- Wire scheduler to broadcast on check completion
- Backwards compatible: page/api modes unchanged

1 files changed, 7 insertions, 1 deletions

diff --git a/cmd/kaze/main.go b/cmd/kaze/main.go
index aaed1fa..b8895a0 100644
--- a/cmd/kaze/main.go
+++ b/cmd/kaze/main.go
@@ -108,6 +108,10 @@ func main() {
 	}
 	srv.SetVersion(version, commit, date)
 
+	sched.SetOnCheckCallback(func() {
+		srv.BroadcastStatusUpdate(context.Background())
+	})
+
 	// Setup graceful shutdown
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
@@ -178,10 +182,12 @@ func main() {
 			return fmt.Errorf("failed to create new scheduler: %w", err)
 		}
 
-		// Swap config/scheduler without restarting the HTTP listener
 		srv.UpdateConfig(newCfg, newSched)
 		cfg = newCfg
 		sched = newSched
+		sched.SetOnCheckCallback(func() {
+			srv.BroadcastStatusUpdate(context.Background())
+		})
 		sched.Start()
 
 		logger.Info("configuration reloaded successfully (zero-downtime)",