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_toml.py

@@ -1,8 +1,9 @@
 """TOML-based graph configuration loader."""
 
-import tomllib
 from pathlib import Path
-from typing import Any, Dict
+from typing import Any
+
+import tomllib
 
 from engine.pipeline.graph import Graph, NodeType
 from engine.pipeline.graph_adapter import graph_to_pipeline
@@ -23,7 +24,7 @@ def load_graph_from_toml(toml_path: str | Path) -> Graph:
     return graph_from_dict(data)
 
 
-def graph_from_dict(data: Dict[str, Any]) -> Graph:
+def graph_from_dict(data: dict[str, Any]) -> Graph:
     """Create a graph from a dictionary (TOML-compatible structure).
 
     Args: