frames: StartFrame is now a SystemFrame

src/pipecat/frames/frames.py

@@ -248,6 +248,16 @@ class SystemFrame(Frame):
     pass
 
 
+@dataclass
+class StartFrame(SystemFrame):
+    """This is the first frame that should be pushed down a pipeline."""
+    clock: BaseClock
+    allow_interruptions: bool = False
+    enable_metrics: bool = False
+    enable_usage_metrics: bool = False
+    report_only_initial_ttfb: bool = False
+
+
 @dataclass
 class CancelFrame(SystemFrame):
     """Indicates that a pipeline needs to stop right away."""
@@ -338,16 +348,6 @@ class ControlFrame(Frame):
     pass
 
 
-@dataclass
-class StartFrame(ControlFrame):
-    """This is the first frame that should be pushed down a pipeline."""
-    clock: BaseClock
-    allow_interruptions: bool = False
-    enable_metrics: bool = False
-    enable_usage_metrics: bool = False
-    report_only_initial_ttfb: bool = False
-
-
 @dataclass
 class EndFrame(ControlFrame):
     """Indicates that a pipeline has ended and frame processors and pipelines