fix: Fix 'q' key handling and connectivity status issues

- Fix 'q' key in detail/add/help screens to return to list instead of quitting
- Only quit application with 'q' when on main list screen
- Fix parseHandshake to accumulate all time units instead of returning early
  This resolves handshake timing discrepancy with wg show output
- Increase connection status threshold from 3 to 5 minutes
  Allows ~12 missed keepalive intervals (25s each)
  Improves connectivity status accuracy for peers with marginal connections

cmd/wg-tui/main.go

@@ -47,10 +47,13 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 
 	switch msg := msg.(type) {
 	case tea.KeyMsg:
-		switch msg.String() {
-		case "q", "ctrl+c":
+		// Only quit on 'q' when on list screen
+		// Other screens handle 'q' to navigate back
+		if _, ok := m.currentScreen.(*screens.ListScreen); ok && (msg.String() == "q" || msg.String() == "ctrl+c") {
 			m.quitting = true
 			return m, tea.Quit
+		}
+		switch msg.String() {
 		case "?":
 			// Switch to help screen
 			m.previousScreen = m.currentScreen