Add tool settings files for configurable tool defaults

Tools can now ship with defaults.yaml containing configurable settings
that users can customize via settings.yaml (auto-created from defaults).

Features:
- ensure_settings() helper copies defaults to settings on first use
- Settings available as {settings.key} in templates (scalars only)
- Full dict access via settings['key'] in code steps
- CLI: cmdforge settings <tool> show/edit/reset/diff
- GUI: Defaults editor in Tool Builder, Configure button on Tools page
- Registry: defaults.yaml published with tools, included in downloads
- Secret detection warning on publish (api_key, password, token, etc.)

Fully backward compatible - tools without defaults work unchanged.

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

src/cmdforge/gui/pages/tools_page.py

@@ -226,6 +226,13 @@ class ToolsPage(QWidget):
         self.btn_edit.setEnabled(False)
         btn_layout.addWidget(self.btn_edit)
 
+        self.btn_configure = QPushButton("Configure")
+        self.btn_configure.setObjectName("secondary")
+        self.btn_configure.setToolTip("Edit tool settings (only available for tools with configurable settings)")
+        self.btn_configure.clicked.connect(self._configure_tool)
+        self.btn_configure.setEnabled(False)
+        btn_layout.addWidget(self.btn_configure)
+
         self.btn_delete = QPushButton("Delete")
         self.btn_delete.setObjectName("danger")
         self.btn_delete.clicked.connect(self._delete_tool)
@@ -582,12 +589,24 @@ class ToolsPage(QWidget):
 
         self.info_text.setHtml("\n".join(lines))
 
+    def _has_settings(self, tool: Tool) -> bool:
+        """Check if a tool has configurable settings."""
+        if not tool or not tool.path:
+            return False
+        defaults_path = tool.path.parent / "defaults.yaml"
+        settings_path = tool.path.parent / "settings.yaml"
+        return defaults_path.exists() or settings_path.exists()
+
     def _update_buttons(self):
         """Update button enabled states."""
         has_selection = self._current_tool is not None
         self.btn_edit.setEnabled(has_selection)
         self.btn_delete.setEnabled(has_selection)
 
+        # Configure button only for tools with settings
+        has_settings = has_selection and self._has_settings(self._current_tool)
+        self.btn_configure.setEnabled(has_settings)
+
         config = load_config()
         if config.registry.token:
             # Connected - enable Publish when tool selected
@@ -605,6 +624,25 @@ class ToolsPage(QWidget):
         if self._current_tool:
             self.main_window.open_tool_builder(self._current_tool.name)
 
+    def _configure_tool(self):
+        """Open settings dialog for the selected tool."""
+        if not self._current_tool:
+            return
+
+        if not self._has_settings(self._current_tool):
+            QMessageBox.information(
+                self,
+                "No Settings",
+                f"Tool '{self._current_tool.name}' has no configurable settings.\n\n"
+                "Add a defaults.yaml to the tool to enable settings."
+            )
+            return
+
+        from ..dialogs.settings_dialog import SettingsDialog
+        dialog = SettingsDialog(self, self._current_tool.name)
+        if dialog.exec():
+            self.main_window.show_status(f"Settings saved for '{self._current_tool.name}'")
+
     def _delete_tool(self):
         """Delete the selected tool."""
         if not self._current_tool: