feat(tui): add status bar, help overlay, tag filter, and entity actions

Status bar with entity count and context-sensitive key hints. Help
overlay via ? key. Tag filter via # with cursor-navigable tag list.
Todo toggle (x), pin (!), promote (p), demote (D), copy (c), edit (e)
via $EDITOR. Delete confirmation with 3s timeout. Date-grouped list
with completed todo and pinned indicators. Esc clears active tag filter.

Adds CompletedAt/ClearCompleted to EntityUpdate for todo toggling.

internal/tui/list.go

@@ -3,6 +3,7 @@ package tui
 import (
 	"fmt"
 	"strings"
+	"time"
 
 	tea "github.com/charmbracelet/bubbletea"
 
@@ -87,18 +88,49 @@ func (l listModel) view(width int) string {
 		return statusStyle.Render("no entities")
 	}
 
-	var b strings.Builder
+	groups := groupByDate(l.entities)
+
+	type displayLine struct {
+		text      string
+		entityIdx int
+		isHeader  bool
+	}
+
+	var lines []displayLine
+	entityIdx := 0
+	for _, g := range groups {
+		lines = append(lines, displayLine{
+			text:     dateHeaderStyle.Render("── " + g.label + " ──"),
+			isHeader: true,
+		})
+		for _, e := range g.entities {
+			line := renderEntity(e, width-4)
+			lines = append(lines, displayLine{
+				text:      line,
+				entityIdx: entityIdx,
+			})
+			entityIdx++
+		}
+	}
+
+	cursorLine := l.cursorDisplayLine(groups)
 	visible := l.visibleCount()
-	end := min(l.offset+visible, len(l.entities))
 
-	for i := l.offset; i < end; i++ {
-		e := l.entities[i]
-		line := renderEntity(e, width-4)
+	offset := 0
+	if cursorLine >= visible {
+		offset = cursorLine - visible + 1
+	}
 
-		if i == l.cursor {
-			b.WriteString(selectedItemStyle.Render(" " + line))
+	var b strings.Builder
+	end := min(offset+visible, len(lines))
+	for i := offset; i < end; i++ {
+		dl := lines[i]
+		if dl.isHeader {
+			b.WriteString(dl.text)
+		} else if dl.entityIdx == l.cursor {
+			b.WriteString(selectedItemStyle.Render(" " + dl.text))
 		} else {
-			b.WriteString(listItemStyle.Render(line))
+			b.WriteString(listItemStyle.Render(dl.text))
 		}
 		if i < end-1 {
 			b.WriteString("\n")
@@ -108,6 +140,22 @@ func (l listModel) view(width int) string {
 	return b.String()
 }
 
+func (l listModel) cursorDisplayLine(groups []dateGroup) int {
+	line := 0
+	entityIdx := 0
+	for _, g := range groups {
+		line++
+		for range g.entities {
+			if entityIdx == l.cursor {
+				return line
+			}
+			line++
+			entityIdx++
+		}
+	}
+	return 0
+}
+
 func (l listModel) visibleCount() int {
 	if l.height <= 0 {
 		return 20
@@ -115,8 +163,44 @@ func (l listModel) visibleCount() int {
 	return l.height
 }
 
+type dateGroup struct {
+	label    string
+	entities []*db.Entity
+}
+
+func groupByDate(entities []*db.Entity) []dateGroup {
+	var groups []dateGroup
+	var current *dateGroup
+
+	for _, e := range entities {
+		label := formatDateLabel(e.CreatedAt)
+		if current == nil || current.label != label {
+			if current != nil {
+				groups = append(groups, *current)
+			}
+			current = &dateGroup{label: label}
+		}
+		current.entities = append(current.entities, e)
+	}
+	if current != nil {
+		groups = append(groups, *current)
+	}
+	return groups
+}
+
+func formatDateLabel(t time.Time) string {
+	return strings.ToLower(t.Format("Jan 2"))
+}
+
 func renderEntity(e *db.Entity, maxWidth int) string {
-	glyph := glyphStyle.Render(display.DisplayGlyph(e.Glyph, e.CardType))
+	glyphStr := display.DisplayGlyph(e.Glyph, e.CardType)
+	style := glyphStyle
+	if e.Glyph == db.GlyphTodo && e.CompletedAt != nil {
+		glyphStr = "●"
+		style = completedGlyphStyle
+	}
+	glyph := style.Render(glyphStr)
+
 	id := idStyle.Render("[" + display.FormatID(e.ID) + "]")
 
 	body := e.Body
@@ -124,20 +208,28 @@ func renderEntity(e *db.Entity, maxWidth int) string {
 		body = *e.Title
 	}
 
-	var tags string
+	var extras []string
+	if e.Pinned {
+		extras = append(extras, pinnedStyle.Render("•"))
+	}
 	if len(e.Tags) > 0 {
 		tagParts := make([]string, len(e.Tags))
 		for i, t := range e.Tags {
 			tagParts[i] = tagStyle.Render("#" + t)
 		}
-		tags = " " + strings.Join(tagParts, " ")
+		extras = append(extras, strings.Join(tagParts, " "))
 	}
 
-	line := fmt.Sprintf("%s %s%s %s", glyph, body, tags, id)
+	extraStr := ""
+	if len(extras) > 0 {
+		extraStr = " " + strings.Join(extras, " ")
+	}
+
+	line := fmt.Sprintf("%s %s%s %s", glyph, body, extraStr, id)
 
 	if maxWidth > 0 && len(stripAnsi(line)) > maxWidth {
 		body = truncate(body, maxWidth-20)
-		line = fmt.Sprintf("%s %s%s %s", glyph, body, tags, id)
+		line = fmt.Sprintf("%s %s%s %s", glyph, body, extraStr, id)
 	}
 
 	return line