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/display/backends/terminal.py

@@ -247,7 +247,7 @@ class TerminalDisplay:
                     keys.append("escape")
                 elif char.isprintable():
                     keys.append(char)
-        except (OSError, IOError):
+        except OSError:
             pass
 
         return keys