feat(ui): change ctrl+c to cancel operations, ctrl+q to quit

Changed keybinding behavior to match common terminal UX:

**ctrl+c**: Cancel ongoing LLM operations without quitting
- Cancels model pulls
- Cancels streaming responses
- Cancels query generation
- Does nothing if no operation is active (no longer quits)

**ctrl+q**: New hard quit keybinding
- Quits the application immediately
- Also callable from top-level (model.go) to cancel any LLM ops before exit
- Shown as "q / ctrl+q" in help screen since 'q' already quits from nav mode

This matches terminal conventions where ctrl+c interrupts the current task
but doesn't exit the program.

Updated:
- Top-level handler in model.go: ctrl+q quits, ctrl+c cancels ops
- Chat completer: ctrl+q quits instead of ctrl+c
- Chat main handler: ctrl+c only cancels, removed quit fallback
- Form help: ctrl+q instead of ctrl+c
- Help screen: "Cancel operation" instead of "Cancel stream"
- Nav mode help: "q / ctrl+q" instead of just "q"

Closes #170

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: cpcloud

internal/app/chat.go

@@ -1076,7 +1076,7 @@ func (m *Model) handleChatKey(key tea.KeyMsg) (tea.Model, tea.Cmd) {
 			}
 			m.deactivateCompleter()
 			return m, nil
-		case "ctrl+c":
+		case "ctrl+q":
 			return m, tea.Interrupt
 		}
 	}
@@ -1094,7 +1094,7 @@ func (m *Model) handleChatKey(key tea.KeyMsg) (tea.Model, tea.Cmd) {
 		m.toggleSQL()
 		return m, nil
 	case "ctrl+c":
-		// Cancel stream or pull, otherwise quit.
+		// Cancel stream or pull if active.
 		if m.chat.Streaming && m.chat.CancelFn != nil {
 			m.chat.CancelFn()
 			m.chat.Streaming = false
@@ -1112,9 +1112,8 @@ func (m *Model) handleChatKey(key tea.KeyMsg) (tea.Model, tea.Cmd) {
 			m.refreshChatViewport()
 			return m, nil
 		}
-		// No active operations -- clean up and quit.
-		m.cancelChatOperations()
-		return m, tea.Interrupt
+		// No active operations -- ctrl+c does nothing in chat.
+		return m, nil
 	case "up", "ctrl+p":
 		if m.chat.Input.Focused() && !m.chat.Streaming {
 			m.historyBack()

internal/app/model.go

@@ -143,10 +143,15 @@ func (m *Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.resizeTables()
 		m.updateAllViewports()
 	case tea.KeyMsg:
-		if typed.String() == "ctrl+c" {
+		if typed.String() == "ctrl+q" {
 			m.cancelChatOperations()
 			return m, tea.Interrupt
 		}
+		if typed.String() == "ctrl+c" {
+			// Cancel any ongoing LLM operations but don't quit.
+			m.cancelChatOperations()
+			return m, nil
+		}
 	case chatChunkMsg:
 		// Chunks arriving after chat is closed are harmlessly dropped.
 		if m.chat != nil {

internal/app/view.go

@@ -251,7 +251,7 @@ func (m *Model) statusView() string {
 			dirtyIndicator,
 			m.helpItem("ctrl+s", "save"),
 			m.helpItem("esc", "cancel"),
-			m.helpItem("ctrl+c", "quit"),
+			m.helpItem("ctrl+q", "quit"),
 		)
 		return m.withStatusMessage(help)
 	}
@@ -776,7 +776,7 @@ func (m *Model) helpContent() string {
 				{"@", "Ask LLM"},
 				{"i", "Edit mode"},
 				{"?", "Help"},
-				{"q", "Quit"},
+				{"q / ctrl+q", "Quit"},
 			},
 		},
 		{
@@ -805,7 +805,7 @@ func (m *Model) helpContent() string {
 				{"enter", "Send message"},
 				{"ctrl+s", "Toggle SQL display"},
 				{"\u2191/\u2193", "Prompt history"},
-				{"ctrl+c", "Cancel stream"},
+				{"ctrl+c", "Cancel operation"},
 				{"esc", "Hide chat"},
 			},
 		},