Add strip_fences option and fix exec() scoping for nested functions

- Add strip_fences field to PromptStep for removing markdown code fences
- Fix exec() to use same dict for globals and locals, allowing nested
  functions to access module-level imports
- Add GUI checkbox for strip_fences option
- Update CLAUDE.md with improved documentation

Co-Authored-By: Claude Opus 4.5 <[email protected]>

src/cmdforge/gui/dialogs/step_dialog.py

@@ -5,7 +5,8 @@ import ast
 from PySide6.QtWidgets import (
     QDialog, QVBoxLayout, QFormLayout, QLineEdit,
     QComboBox, QPushButton, QHBoxLayout, QLabel,
-    QPlainTextEdit, QSplitter, QGroupBox, QTextEdit, QMessageBox
+    QPlainTextEdit, QSplitter, QGroupBox, QTextEdit, QMessageBox,
+    QCheckBox
 )
 from PySide6.QtCore import Qt, QThread, Signal
 
@@ -68,6 +69,10 @@ class PromptStepDialog(QDialog):
         self.output_input.setText("response")
         form.addRow("Output variable:", self.output_input)
 
+        # Strip fences checkbox
+        self.strip_fences_check = QCheckBox("Strip markdown code fences from output")
+        form.addRow("", self.strip_fences_check)
+
         layout.addLayout(form)
 
         # Prompt text
@@ -118,6 +123,7 @@ class PromptStepDialog(QDialog):
 
         self.output_input.setText(step.output_var)
         self.prompt_input.setPlainText(step.prompt)
+        self.strip_fences_check.setChecked(step.strip_fences)
 
     def _validate_and_accept(self):
         """Validate and accept."""
@@ -146,7 +152,8 @@ class PromptStepDialog(QDialog):
             provider=self.provider_combo.currentText(),
             output_var=self.output_input.text().strip(),
             profile=profile,
-            name=name
+            name=name,
+            strip_fences=self.strip_fences_check.isChecked()
         )