feat(cli): add nib add + nib ls commands

Default command delegation: `nib "..."` routes to `nib add`. Capture
bar parses grammar, creates entities. `nib ls` lists with date
grouping, tag filter, 48h default window. Display glyphs for all
entity types.

internal/display/glyph.go

@@ -0,0 +1,36 @@
+package display
+
+import "github.com/lerko/nib/internal/db"
+
+var glyphMap = map[db.Glyph]string{
+	db.GlyphNote:  "◦",
+	db.GlyphTodo:  "▸",
+	db.GlyphEvent: "◇",
+}
+
+var cardGlyphMap = map[db.CardType]string{
+	db.CardSnippet:   "◆",
+	db.CardTemplate:  "◈",
+	db.CardChecklist: "☐",
+	db.CardDecision:  "⚖",
+	db.CardLink:      "🔗",
+}
+
+func DisplayGlyph(glyph db.Glyph, cardType *db.CardType) string {
+	if cardType != nil {
+		if g, ok := cardGlyphMap[*cardType]; ok {
+			return g
+		}
+	}
+	if g, ok := glyphMap[glyph]; ok {
+		return g
+	}
+	return "◦"
+}
+
+func FormatID(id string) string {
+	if len(id) > 6 {
+		return id[:6]
+	}
+	return id
+}