feat(tui): stumble mode — resurface stale entries card by card

Card-by-card walkthrough of entries untouched for 30+ days.
Prevents write-mostly decay by bringing old entries back to attention.

- S from list triggers stumble, loads entries where modified_at < 30d
- Single-card view with markdown body, glyph, tags, age indicator
- Actions: n skip, d dismiss, ! pin, p promote, m absorb, esc exit
- Progress indicator: stumble [3/12]
- After promote/absorb from stumble, returns to deck (not list)
- "All caught up" screen when deck exhausted
- DB: add ModifiedBefore to ListParams, modified_at sort column

internal/tui/model.go

@@ -22,6 +22,7 @@ const (
 	stateConfirm
 	statePromote
 	stateAbsorb
+	stateStumble
 )
 
 type viewMode int
@@ -85,6 +86,7 @@ type model struct {
 	promote  promoteModel
 	absorb   absorbModel
 	tagRail  tagRailModel
+	stumble  stumbleModel
 	showHelp bool
 
 	focus       focusPane
@@ -231,8 +233,13 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		return m, tea.Batch(loadEntities(m.store, m.listParams()), m.setStatus(msg.action))
 
 	case entityPromotedMsg:
-		m.state = stateList
-		return m, tea.Batch(loadEntities(m.store, m.listParams()), m.setStatus(fmt.Sprintf("promoted → %s", msg.cardType)))
+		if !m.stumble.done && len(m.stumble.entries) > 0 {
+			m.stumble.advance()
+			m.state = stateStumble
+		} else {
+			m.state = stateList
+		}
+		return m, tea.Batch(loadEntities(m.store, m.listParams()), loadRailTags(m.store), m.setStatus(fmt.Sprintf("promoted → %s", msg.cardType)))
 
 	case entityDemotedMsg:
 		return m, tea.Batch(m.reloadDetail(msg.id), m.setStatus("demoted → fluid"))
@@ -241,7 +248,12 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		return m, m.setStatus("copied")
 
 	case entityAbsorbedMsg:
-		m.state = stateList
+		if !m.stumble.done && len(m.stumble.entries) > 0 {
+			m.stumble.advance()
+			m.state = stateStumble
+		} else {
+			m.state = stateList
+		}
 		return m, tea.Batch(loadEntities(m.store, m.listParams()), loadRailTags(m.store), m.setStatus("absorbed"))
 
 	case absorbSourcesLoadedMsg:
@@ -265,6 +277,16 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.state = stateTagFilter
 		return m, nil
 
+	case staleEntitiesLoadedMsg:
+		m.stumble = newStumbleModel()
+		m.stumble.setEntries(msg.entities)
+		m.stumble.setSize(m.width, m.contentHeight())
+		m.state = stateStumble
+		return m, nil
+
+	case stumbleActionMsg:
+		return m, m.setStatus(msg.action)
+
 	case editorFinishedMsg:
 		if msg.err != nil {
 			m.err = msg.err
@@ -300,6 +322,8 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			return m.updatePromote(msg)
 		case stateAbsorb:
 			return m.updateAbsorb(msg)
+		case stateStumble:
+			return m.updateStumble(msg)
 		default:
 			return m.updateKeys(msg)
 		}
@@ -532,6 +556,12 @@ func (m model) updateBrowse(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 		}
 		return m, nil
 
+	case "S":
+		if m.state == stateList {
+			return m, loadStaleEntities(m.store)
+		}
+		return m, nil
+
 	case "i":
 		if m.mode == modeCards && m.state == stateList {
 			m.cards.setIntent(m.cards.intent.next())
@@ -818,6 +848,57 @@ func (m model) updateAbsorb(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 	}
 }
 
+func (m model) updateStumble(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
+	if m.stumble.done {
+		m.state = stateList
+		return m, loadEntities(m.store, m.listParams())
+	}
+
+	switch msg.String() {
+	case "esc", "q":
+		m.state = stateList
+		return m, loadEntities(m.store, m.listParams())
+	case "n", "right":
+		m.stumble.advance()
+		if m.stumble.done {
+			return m, m.setStatus("all caught up")
+		}
+		return m, nil
+	case "d":
+		e := m.stumble.current()
+		if e != nil {
+			m.stumble.removeCurrent()
+			return m, stumbleDismiss(m.store, e.ID)
+		}
+		return m, nil
+	case "!":
+		e := m.stumble.current()
+		if e != nil {
+			m.stumble.advance()
+			return m, stumblePin(m.store, e.ID)
+		}
+		return m, nil
+	case "p":
+		e := m.stumble.current()
+		if e != nil {
+			m.promote = newPromoteModel(e.ID, e.Body)
+			m.state = statePromote
+			return m, nil
+		}
+		return m, nil
+	case "m":
+		e := m.stumble.current()
+		if e != nil {
+			if e.CardType != nil {
+				return m, m.setStatus("target must be fluid")
+			}
+			return m, loadAbsorbSources(m.store, e.ID)
+		}
+		return m, nil
+	}
+	return m, nil
+}
+
 func (m model) View() string {
 	if m.showHelp {
 		return renderHelp(m.width, m.height)
@@ -852,6 +933,8 @@ func (m model) View() string {
 		content = m.promote.view(m.width)
 	case stateAbsorb:
 		content = m.absorb.view(m.width)
+	case stateStumble:
+		content = m.stumble.view()
 	}
 
 	header := m.headerView()