feat: add supervisor prototype with embedded frontend

internal/ws/messages.go

@@ -0,0 +1,31 @@
+package ws
+
+import "encoding/json"
+
+type Envelope struct {
+	Type    string          `json:"type"`
+	Session string          `json:"session"`
+	Payload json.RawMessage `json:"payload"`
+}
+
+type TerminalInputPayload struct {
+	Data string `json:"data"`
+}
+
+type TerminalOutputPayload struct {
+	Data string `json:"data"`
+}
+
+type TerminalResizePayload struct {
+	Cols int `json:"cols"`
+	Rows int `json:"rows"`
+}
+
+type SessionStatusPayload struct {
+	Status   string `json:"status"`
+	ExitCode *int   `json:"exitCode,omitempty"`
+}
+
+type ErrorPayload struct {
+	Message string `json:"message"`
+}