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.

internal/tui/keys.go

@@ -0,0 +1,33 @@
+package tui
+
+import "github.com/charmbracelet/bubbles/key"
+
+type keyMap struct {
+	Up     key.Binding
+	Down   key.Binding
+	Enter  key.Binding
+	Back   key.Binding
+	Add    key.Binding
+	Delete key.Binding
+	Quit   key.Binding
+	Help   key.Binding
+	PageUp key.Binding
+	PageDn key.Binding
+	Top    key.Binding
+	Bottom key.Binding
+}
+
+var keys = keyMap{
+	Up:     key.NewBinding(key.WithKeys("up", "k"), key.WithHelp("↑/k", "up")),
+	Down:   key.NewBinding(key.WithKeys("down", "j"), key.WithHelp("↓/j", "down")),
+	Enter:  key.NewBinding(key.WithKeys("enter"), key.WithHelp("enter", "view")),
+	Back:   key.NewBinding(key.WithKeys("esc"), key.WithHelp("esc", "back")),
+	Add:    key.NewBinding(key.WithKeys("a"), key.WithHelp("a", "add")),
+	Delete: key.NewBinding(key.WithKeys("d"), key.WithHelp("d", "delete")),
+	Quit:   key.NewBinding(key.WithKeys("q", "ctrl+c"), key.WithHelp("q", "quit")),
+	Help:   key.NewBinding(key.WithKeys("?"), key.WithHelp("?", "help")),
+	PageUp: key.NewBinding(key.WithKeys("pgup", "ctrl+u"), key.WithHelp("pgup", "page up")),
+	PageDn: key.NewBinding(key.WithKeys("pgdown", "ctrl+d"), key.WithHelp("pgdn", "page down")),
+	Top:    key.NewBinding(key.WithKeys("home", "g"), key.WithHelp("home", "top")),
+	Bottom: key.NewBinding(key.WithKeys("end", "G"), key.WithHelp("end", "bottom")),
+}