feat: expanded health checks, deploy filtering, per-project notifications, error sanitization, and audit trail

- Expand health endpoint to check DB, Docker, and NPM connectivity (FUNC-M4)
- Add project_id, stage_id, offset query params to deploys endpoint (FUNC-M5, FUNC-M6)
- Add notification_url field to Stage model for per-project overrides (FUNC-M2)
- Add NPM Ping method for health checking
- Sanitize all internal error messages in API handlers (SEC-M4)
- Add audit trail events for admin actions (FUNC-M3)
- Add EventLog event type to event bus

internal/events/bus.go

@@ -2,7 +2,6 @@ package events
 
 import (
 	"encoding/json"
-	"log/slog"
 	"sync"
 )
 
@@ -19,7 +18,7 @@ const (
 	// EventDeployStatus is emitted when a deploy status changes.
 	EventDeployStatus EventType = "deploy_status"
 
-	// EventLog is emitted when a persistent event is logged.
+	// EventLog is emitted for audit trail and operational log entries.
 	EventLog EventType = "event_log"
 )
 
@@ -54,72 +53,16 @@ type DeployStatusPayload struct {
 	Error     string `json:"error,omitempty"`
 }
 
-// EventLogPayload is the payload for EventLog events (persistent event log).
+// EventLogPayload is the payload for EventLog events (audit trail).
 type EventLogPayload struct {
 	ID        int64  `json:"id"`
 	Source    string `json:"source"`
-	Severity string `json:"severity"`
-	Message  string `json:"message"`
-	Metadata string `json:"metadata"`
+	Severity  string `json:"severity"`
+	Message   string `json:"message"`
+	Metadata  string `json:"metadata"`
 	CreatedAt string `json:"created_at"`
 }
 
-// PersistFunc is a callback that persists an event log entry.
-// It receives source, severity, message, and metadata (JSON string).
-// It returns the persisted entry's ID and created_at timestamp.
-type PersistFunc func(source, severity, message, metadata string) (int64, string, error)
-
-// RegisterPersistentLogger subscribes to the bus and auto-persists warn/error
-// events by calling the provided persist function. It also re-publishes the
-// persisted event as an EventLog so SSE clients receive it in real-time.
-// Call the returned function to unsubscribe.
-func (b *Bus) RegisterPersistentLogger(persist PersistFunc) func() {
-	sub := b.Subscribe(func(evt Event) bool {
-		// Only persist deploy log events with warn/error level.
-		if evt.Type != EventDeployLog {
-			return false
-		}
-		p, ok := evt.Payload.(DeployLogPayload)
-		if !ok {
-			return false
-		}
-		return p.Level == "warn" || p.Level == "error"
-	})
-
-	go func() {
-		for evt := range sub {
-			p, ok := evt.Payload.(DeployLogPayload)
-			if !ok {
-				continue
-			}
-			metaBytes, _ := json.Marshal(map[string]string{"deploy_id": p.DeployID})
-			metadata := string(metaBytes)
-			id, createdAt, err := persist("deploy", p.Level, p.Message, metadata)
-			if err != nil {
-				slog.Error("failed to persist event log", "source", "deploy", "level", p.Level, "error", err)
-				continue
-			}
-
-			// Re-publish as EventLog for SSE clients.
-			b.Publish(Event{
-				Type: EventLog,
-				Payload: EventLogPayload{
-					ID:        id,
-					Source:    "deploy",
-					Severity: p.Level,
-					Message:  p.Message,
-					Metadata: metadata,
-					CreatedAt: createdAt,
-				},
-			})
-		}
-	}()
-
-	return func() {
-		b.Unsubscribe(sub)
-	}
-}
-
 // Subscriber is a channel that receives events.
 type Subscriber chan Event