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/cards.go

@@ -0,0 +1,262 @@
+package tui
+
+import (
+	"fmt"
+	"strings"
+
+	tea "github.com/charmbracelet/bubbletea"
+
+	"github.com/lerko/nib/internal/db"
+	"github.com/lerko/nib/internal/display"
+)
+
+type intent int
+
+const (
+	intentAll intent = iota
+	intentGrab
+	intentRead
+	intentFill
+)
+
+func (i intent) String() string {
+	switch i {
+	case intentGrab:
+		return "grab"
+	case intentRead:
+		return "read"
+	case intentFill:
+		return "fill"
+	default:
+		return "all"
+	}
+}
+
+func (i intent) next() intent {
+	switch i {
+	case intentAll:
+		return intentGrab
+	case intentGrab:
+		return intentRead
+	case intentRead:
+		return intentFill
+	default:
+		return intentAll
+	}
+}
+
+func matchesIntent(e *db.Entity, i intent) bool {
+	if i == intentAll {
+		return true
+	}
+	ct := e.CardType
+	if ct == nil {
+		return i == intentGrab
+	}
+	switch i {
+	case intentGrab:
+		return *ct == db.CardSnippet
+	case intentRead:
+		return *ct == db.CardNote || *ct == db.CardLink || *ct == db.CardDecision
+	case intentFill:
+		return *ct == db.CardTemplate || *ct == db.CardChecklist
+	}
+	return false
+}
+
+type cardsModel struct {
+	entities []*db.Entity
+	filtered []*db.Entity
+	cursor   int
+	offset   int
+	height   int
+	width    int
+	intent   intent
+}
+
+func newCardsModel() cardsModel {
+	return cardsModel{}
+}
+
+func (c *cardsModel) setEntities(entities []*db.Entity) {
+	c.entities = entities
+	c.applyFilter()
+}
+
+func (c *cardsModel) setIntent(i intent) {
+	c.intent = i
+	c.cursor = 0
+	c.offset = 0
+	c.applyFilter()
+}
+
+func (c *cardsModel) applyFilter() {
+	c.filtered = nil
+	var pinned, rest []*db.Entity
+	for _, e := range c.entities {
+		if !matchesIntent(e, c.intent) {
+			continue
+		}
+		if e.Pinned {
+			pinned = append(pinned, e)
+		} else {
+			rest = append(rest, e)
+		}
+	}
+	c.filtered = append(pinned, rest...)
+	if c.cursor >= len(c.filtered) {
+		c.cursor = max(0, len(c.filtered)-1)
+	}
+}
+
+func (c *cardsModel) setSize(width, height int) {
+	c.width = width
+	c.height = height
+}
+
+func (c cardsModel) selected() *db.Entity {
+	if len(c.filtered) == 0 || c.cursor >= len(c.filtered) {
+		return nil
+	}
+	return c.filtered[c.cursor]
+}
+
+func (c cardsModel) update(msg tea.KeyMsg) cardsModel {
+	switch msg.String() {
+	case "up", "k":
+		if c.cursor > 0 {
+			c.cursor--
+			if c.cursor < c.offset {
+				c.offset = c.cursor
+			}
+		}
+	case "down", "j":
+		if c.cursor < len(c.filtered)-1 {
+			c.cursor++
+			visible := c.visibleCount()
+			if c.cursor >= c.offset+visible {
+				c.offset = c.cursor - visible + 1
+			}
+		}
+	case "home", "g":
+		c.cursor = 0
+		c.offset = 0
+	case "end", "G":
+		c.cursor = max(0, len(c.filtered)-1)
+		visible := c.visibleCount()
+		if c.cursor >= visible {
+			c.offset = c.cursor - visible + 1
+		}
+	case "pgup", "ctrl+u":
+		c.cursor = max(0, c.cursor-c.visibleCount())
+		if c.cursor < c.offset {
+			c.offset = c.cursor
+		}
+	case "pgdown", "ctrl+d":
+		c.cursor = min(len(c.filtered)-1, c.cursor+c.visibleCount())
+		visible := c.visibleCount()
+		if c.cursor >= c.offset+visible {
+			c.offset = c.cursor - visible + 1
+		}
+	}
+	return c
+}
+
+func (c cardsModel) view(width int) string {
+	if len(c.filtered) == 0 {
+		return statusStyle.Render("no cards")
+	}
+
+	var b strings.Builder
+	visible := c.visibleCount()
+	end := min(c.offset+visible, len(c.filtered))
+
+	for i := c.offset; i < end; i++ {
+		e := c.filtered[i]
+		line := renderCard(e, width-4)
+
+		if i == c.cursor {
+			b.WriteString(selectedItemStyle.Render(" " + line))
+		} else {
+			b.WriteString(listItemStyle.Render(line))
+		}
+		if i < end-1 {
+			b.WriteString("\n")
+		}
+	}
+
+	return b.String()
+}
+
+func (c cardsModel) visibleCount() int {
+	if c.height <= 0 {
+		return 20
+	}
+	return c.height
+}
+
+func renderCard(e *db.Entity, maxWidth int) string {
+	glyph := glyphStyle.Render(display.DisplayGlyph(e.Glyph, e.CardType))
+	id := idStyle.Render("[" + display.FormatID(e.ID) + "]")
+
+	body := e.Body
+	if e.Title != nil {
+		body = *e.Title
+	}
+
+	affordance := detectAffordance(e)
+	affordStr := ""
+	if affordance != "" {
+		affordStr = " " + affordanceStyle.Render(affordance)
+	}
+
+	var extras []string
+	if e.Pinned {
+		extras = append(extras, pinnedStyle.Render("•"))
+	}
+	if len(e.Tags) > 0 {
+		limit := min(2, len(e.Tags))
+		for _, t := range e.Tags[:limit] {
+			extras = append(extras, tagStyle.Render("#"+t))
+		}
+	}
+
+	extraStr := ""
+	if len(extras) > 0 {
+		extraStr = " " + strings.Join(extras, " ")
+	}
+
+	useStr := ""
+	if e.UseCount > 0 {
+		useStr = " " + useCountStyle.Render(fmt.Sprintf("%d×", e.UseCount))
+	}
+
+	line := fmt.Sprintf("%s %s%s%s%s %s", glyph, body, affordStr, extraStr, useStr, id)
+
+	if maxWidth > 0 && len(stripAnsi(line)) > maxWidth {
+		body = truncate(body, maxWidth-30)
+		line = fmt.Sprintf("%s %s%s%s%s %s", glyph, body, affordStr, extraStr, useStr, id)
+	}
+
+	return line
+}
+
+func detectAffordance(e *db.Entity) string {
+	if e.CardType == nil {
+		return ""
+	}
+	switch *e.CardType {
+	case db.CardSnippet:
+		return "code"
+	case db.CardTemplate:
+		return "fill"
+	case db.CardChecklist:
+		return "steps"
+	case db.CardDecision:
+		return "decide"
+	case db.CardLink:
+		return "link"
+	default:
+		return ""
+	}
+}