feat: TUI Key & Snippet Management - Task 19

- KeyListTab: view/add/edit/delete SSH keys (Ctrl+K from host list)
- KeyFormTab: add/edit key form with name, type, private key, passphrase
- SnippetListTab: view/add/edit/delete snippets (Ctrl+P from host list)
- SnippetFormTab: add/edit snippet form with name, command, description, tags
- Updated status bar with new hints
- Save/delete commands for both key pairs and snippets

pkg/tui/tabs.go

@@ -196,6 +196,6 @@ func renderTabBar(tm *TabManager) string {
 
 // renderStatusBar renders the bottom status bar
 func renderStatusBar(tm *TabManager) string {
-	hints := "Ctrl+Tab:switch  Ctrl+Q:close  ↑↓:nav  Enter:select  q:quit"
+	hints := "Ctrl+Tab:switch  Ctrl+Q:close  ↑↓:nav  Enter:select  Ctrl+N:add  Ctrl+F:SFTP  Ctrl+K:keys  Ctrl+P:snippets  q:quit"
 	return StatusBarStyle.Render(hints)
 }