feat(tui): add bubbletea terminal UI with entity list, detail, and capture

Adds `nib tui` command and `make tui` target. Scrollable entity list
with j/k navigation, enter for detail view, `a` to capture new entries
using the existing parse grammar, and `d` to delete.

cmd/tui.go

@@ -0,0 +1,25 @@
+package cmd
+
+import (
+	"github.com/lerko/nib/internal/tui"
+	"github.com/spf13/cobra"
+)
+
+var tuiCmd = &cobra.Command{
+	Use:   "tui",
+	Short: "launch the terminal UI",
+	RunE:  runTUI,
+}
+
+func init() {
+	rootCmd.AddCommand(tuiCmd)
+}
+
+func runTUI(_ *cobra.Command, _ []string) error {
+	store, err := openStore()
+	if err != nil {
+		return err
+	}
+	defer store.Close()
+	return tui.Run(store)
+}