Add REPL effect detection and input handling to pipeline runner

- Detect REPL effect in pipeline and enable interactive mode
- Enable raw terminal mode for REPL input capture
- Add keyboard input loop for REPL commands (return, up/down arrows, backspace)
- Process commands and handle pipeline mutations from REPL
- Fix lint issues in graph and REPL modules (type annotations, imports)

engine/pipeline/graph_adapter.py

@@ -4,12 +4,12 @@ This module bridges the new graph-based abstraction with the existing
 Stage-based pipeline system for backward compatibility.
 """
 
-from typing import Dict, Any, List, Optional
+from typing import Any, Optional
 
-from engine.pipeline.graph import Graph, NodeType
-from engine.pipeline.controller import Pipeline, PipelineConfig
-from engine.pipeline.core import PipelineContext
-from engine.pipeline.params import PipelineParams
+from engine.camera import Camera
+from engine.data_sources.sources import EmptyDataSource, HeadlinesDataSource
+from engine.display import DisplayRegistry
+from engine.effects import get_registry
 from engine.pipeline.adapters import (
     CameraStage,
     DataSourceStage,
@@ -18,15 +18,12 @@ from engine.pipeline.adapters import (
     FontStage,
     MessageOverlayStage,
     PositionStage,
-    ViewportFilterStage,
-    create_stage_from_display,
-    create_stage_from_effect,
 )
 from engine.pipeline.adapters.positioning import PositioningMode
-from engine.display import DisplayRegistry
-from engine.effects import get_registry
-from engine.data_sources.sources import EmptyDataSource, HeadlinesDataSource
-from engine.camera import Camera
+from engine.pipeline.controller import Pipeline, PipelineConfig
+from engine.pipeline.core import PipelineContext
+from engine.pipeline.graph import Graph, NodeType
+from engine.pipeline.params import PipelineParams
 
 
 class GraphAdapter:
@@ -34,8 +31,8 @@ class GraphAdapter:
 
     def __init__(self, graph: Graph):
         self.graph = graph
-        self.pipeline: Optional[Pipeline] = None
-        self.context: Optional[PipelineContext] = None
+        self.pipeline: Pipeline | None = None
+        self.context: PipelineContext | None = None
 
     def build_pipeline(
         self, viewport_width: int = 80, viewport_height: int = 24
@@ -154,7 +151,7 @@ def graph_to_pipeline(
 
 
 def dict_to_pipeline(
-    data: Dict[str, Any], viewport_width: int = 80, viewport_height: int = 24
+    data: dict[str, Any], viewport_width: int = 80, viewport_height: int = 24
 ) -> Pipeline:
     """Convert a dictionary to a Pipeline."""
     graph = Graph().from_dict(data)