feat(tui): add cards view, mode switching, promote picker, and card detail

Stream/cards toggle with 1/2 keys. Cards view with intent filtering
(tab cycles grab/read/fill/all), sort cycling (s key), pinned-first
ordering, and affordance badges. Promote picker (p key) with card type
selection and auto-detection from body content. Detail view renders
card_data per type: checklist steps, template slots, decision fields,
link URLs.

Extracts generateCardData to internal/carddata for reuse across cmd
and tui packages.

internal/tui/promote.go

@@ -0,0 +1,84 @@
+package tui
+
+import (
+	"github.com/lerko/nib/internal/carddata"
+	"github.com/lerko/nib/internal/db"
+	"github.com/lerko/nib/internal/display"
+)
+
+type promoteOption struct {
+	cardType db.CardType
+	label    string
+	group    string
+}
+
+var promoteOptions = []promoteOption{
+	{db.CardSnippet, "snippet", "grab"},
+	{db.CardNote, "note", "read"},
+	{db.CardLink, "link", "read"},
+	{db.CardDecision, "decision", "read"},
+	{db.CardTemplate, "template", "fill"},
+	{db.CardChecklist, "checklist", "fill"},
+}
+
+type promoteModel struct {
+	cursor    int
+	entityID  string
+	body      string
+	suggested *db.CardType
+}
+
+func newPromoteModel(entityID, body string) promoteModel {
+	return promoteModel{
+		entityID:  entityID,
+		body:      body,
+		suggested: carddata.DetectCardType(body),
+	}
+}
+
+func (p promoteModel) selectedType() db.CardType {
+	return promoteOptions[p.cursor].cardType
+}
+
+func (p promoteModel) update(key string) promoteModel {
+	switch key {
+	case "up", "k":
+		if p.cursor > 0 {
+			p.cursor--
+		}
+	case "down", "j":
+		if p.cursor < len(promoteOptions)-1 {
+			p.cursor++
+		}
+	}
+	return p
+}
+
+func (p promoteModel) view(width int) string {
+	var b string
+	b += titleStyle.Render("promote to card") + "\n\n"
+
+	currentGroup := ""
+	for i, opt := range promoteOptions {
+		if opt.group != currentGroup {
+			currentGroup = opt.group
+			b += dateHeaderStyle.Render("── "+currentGroup+" ──") + "\n"
+		}
+
+		glyph := display.DisplayGlyph(db.GlyphNote, &opt.cardType)
+		label := glyph + " " + opt.label
+
+		if p.suggested != nil && *p.suggested == opt.cardType {
+			label += " " + affordanceStyle.Render("*")
+		}
+
+		if i == p.cursor {
+			b += selectedItemStyle.Render(" "+label) + "\n"
+		} else {
+			b += listItemStyle.Render(label) + "\n"
+		}
+	}
+
+	b += "\n" + helpStyle.Render("enter:select  esc:cancel")
+	return b
+}