Change primary help key to Ctrl+h (with F1 and Ctrl+? fallbacks)

- Ctrl+h is more mnemonic (h = help) and easier to type
- F1 and Ctrl+? still work as alternatives
- Updated status bar to show 'Ctrl+h help'
- Tested successfully in tmux with all three key combinations
- Updated documentation to reflect Ctrl+h as primary

Assisted-By: docker-agent

Author: masegraye

docs/HELP_DIALOG.md

@@ -6,7 +6,7 @@ The cagent TUI now includes a contextual help dialog that displays all currently
 
 ## Usage
 
-Press **F1** to open the help dialog. (Alternatively, **Ctrl+?** also works in terminals that support keyboard enhancements.)
+Press **Ctrl+h** to open the help dialog. (Alternatively, **F1** or **Ctrl+?** also work.)
 
 The dialog will show all key bindings that are currently active based on:
 - Which panel is focused (content view vs editor)
@@ -63,7 +63,12 @@ The help dialog will pick this up automatically when it's included in any `Bindi
 
 ## Key Binding Notes
 
-**F1** is used as the primary help key because it's universally supported across all terminals. **Ctrl+?** (Ctrl+Shift+/) is also supported as an alternative, but requires terminals with keyboard enhancement support (kitty protocol).
+**Ctrl+h** is used as the primary help key because:
+- It's mnemonic (h = help)
+- It's universally supported across all terminals
+- It's easy to remember and type
+
+**F1** and **Ctrl+?** are also supported as alternatives. Ctrl+? requires terminals with keyboard enhancement support (kitty protocol).
 
 ## Related Files
 

pkg/tui/tui.go

@@ -1578,8 +1578,8 @@ func (m *appModel) Bindings() []key.Binding {
 	))
 
 	bindings = append(bindings, key.NewBinding(
-		key.WithKeys("f1"),
-		key.WithHelp("F1", "help"),
+		key.WithKeys("ctrl+h"),
+		key.WithHelp("Ctrl+h", "help"),
 	))
 
 	// Show newline help based on keyboard enhancement support
@@ -1693,7 +1693,7 @@ func (m *appModel) handleKeyPress(msg tea.KeyPressMsg) (tea.Model, tea.Cmd) {
 	case key.Matches(msg, key.NewBinding(key.WithKeys("ctrl+x"))):
 		return m, core.CmdHandler(messages.ClearQueueMsg{})
 
-	case key.Matches(msg, key.NewBinding(key.WithKeys("ctrl+?", "f1"))):
+	case key.Matches(msg, key.NewBinding(key.WithKeys("ctrl+h", "f1", "ctrl+?"))):
 		// Show contextual help dialog with all currently active key bindings
 		return m, core.CmdHandler(dialog.OpenDialogMsg{
 			Model: dialog.NewHelpDialog(m.Bindings()),