fix(tui): allow question mark to be typed in input field

Fixes bounty issue #1708

The '?' key was globally bound to show help, but in Input context (when
typing in the input field), there was no override binding. This caused
the help popup to appear instead of inserting the '?' character.

Added an Input-context binding for '?' that returns KeyAction::None,
allowing the character to be inserted normally when typing.

Author: factorydroid

cortex-tui/src/actions.rs

@@ -736,6 +736,12 @@ impl ActionMapper {
                 KeyAction::SelectAll,
                 "Select all",
             ),
+            // Allow '?' to be typed as a character (override global Help binding)
+            KeyBinding::input(
+                KeyEvent::new(KeyCode::Char('?'), KeyModifiers::NONE),
+                KeyAction::None,
+                "Insert ?",
+            ),
         ]);
 
         // === Chat context bindings ===