Add barebones but working implementation of model preload (#209, #235)

Add barebones but working implementation of model preload

* add config test for Preload hook
* improve TestProxyManager_StartupHooks
* docs for new hook configuration
* add a .dev to .gitignore

proxy/events.go

@@ -7,6 +7,7 @@ const ChatCompletionStatsEventID = 0x02
 const ConfigFileChangedEventID = 0x03
 const LogDataEventID = 0x04
 const TokenMetricsEventID = 0x05
+const ModelPreloadedEventID = 0x06
 
 type ProcessStateChangeEvent struct {
 	ProcessName string
@@ -48,3 +49,12 @@ type LogDataEvent struct {
 func (e LogDataEvent) Type() uint32 {
 	return LogDataEventID
 }
+
+type ModelPreloadedEvent struct {
+	ModelName string
+	Success   bool
+}
+
+func (e ModelPreloadedEvent) Type() uint32 {
+	return ModelPreloadedEventID
+}