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, 19 insertions, 10 deletions

diff --git a/internal/monitor/scheduler.go b/internal/monitor/scheduler.go
index 809bab5..0d584ea 100644
--- a/internal/monitor/scheduler.go
+++ b/internal/monitor/scheduler.go
@@ -10,16 +10,18 @@ import (
 	"github.com/Fuwn/kaze/internal/storage"
 )
 
-// Scheduler manages and runs all monitors
+type OnCheckCallback func()
+
 type Scheduler struct {
-	monitors   []Monitor
-	monitorCfg map[string]config.MonitorConfig // Monitor configs by ID (group/name) for reset flag checks
-	configPath string
-	storage    *storage.Storage
-	logger     *slog.Logger
-	wg         sync.WaitGroup
-	ctx        context.Context
-	cancel     context.CancelFunc
+	monitors    []Monitor
+	monitorCfg  map[string]config.MonitorConfig
+	configPath  string
+	storage     *storage.Storage
+	logger      *slog.Logger
+	wg          sync.WaitGroup
+	ctx         context.Context
+	cancel      context.CancelFunc
+	onCheckDone OnCheckCallback
 }
 
 // NewScheduler creates a new monitor scheduler
@@ -197,6 +199,10 @@ func (s *Scheduler) executeCheck(mon Monitor) {
 	}
 
 	s.storage.RecordCheck()
+
+	if s.onCheckDone != nil {
+		s.onCheckDone()
+	}
 }
 
 // runCleanup periodically cleans up old data
@@ -247,11 +253,14 @@ func (s *Scheduler) runMaintenance() {
 	}
 }
 
-// GetMonitors returns all registered monitors
 func (s *Scheduler) GetMonitors() []Monitor {
 	return s.monitors
 }
 
+func (s *Scheduler) SetOnCheckCallback(cb OnCheckCallback) {
+	s.onCheckDone = cb
+}
+
 // RunCheck manually triggers a check for a specific monitor by ID (group/name format)
 func (s *Scheduler) RunCheck(id string) *Result {
 	for _, mon := range s.monitors {