feat: add WebSocket handler with token auth and session management

internal/ws/protocol.go

@@ -0,0 +1,41 @@
+package ws
+
+import "encoding/json"
+
+// ── Client → Server messages ──
+
+// MsgType enumerates known message types.
+type MsgType string
+
+const (
+	MsgStart MsgType = "start" // Begin recording session
+	MsgStop  MsgType = "stop"  // End recording session
+	MsgPaste MsgType = "paste" // Re-paste a history item
+)
+
+// ClientMsg is a JSON control message from the phone.
+type ClientMsg struct {
+	Type MsgType `json:"type"`
+	Text string  `json:"text,omitempty"` // Only for "paste"
+}
+
+// ── Server → Client messages ──
+
+const (
+	MsgPartial MsgType = "partial" // Interim ASR result
+	MsgFinal   MsgType = "final"   // Final ASR result
+	MsgPasted  MsgType = "pasted"  // Paste confirmed
+	MsgError   MsgType = "error"   // Error notification
+)
+
+// ServerMsg is a JSON message sent to the phone.
+type ServerMsg struct {
+	Type    MsgType `json:"type"`
+	Text    string  `json:"text,omitempty"`
+	Message string  `json:"message,omitempty"` // For errors
+}
+
+func (m ServerMsg) Bytes() []byte {
+	b, _ := json.Marshal(m)
+	return b
+}