fix(tui): simplify focus model — tab toggles capture ↔ list only

Tag rail removed from tab cycle to reduce focus confusion.
Rail is now ambient-by-default, focusable via h from list (spatial).

- Tab: capture ↔ list (no rail, no detail in cycle)
- h from list: focus tag rail (when visible)
- l from rail: back to list
- Split detail reachable via l/enter, not tab
- Remove nextFocusFromCapture helper

internal/tui/model.go

@@ -333,13 +333,6 @@ func (m model) updateKeys(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 	return m.updateBrowse(msg)
 }
 
-func (m model) nextFocusFromCapture() focusPane {
-	if m.railVisible() {
-		return focusTagRail
-	}
-	return focusList
-}
-
 func (m model) updateCapture(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 	switch msg.String() {
 	case "enter":
@@ -364,12 +357,9 @@ func (m model) updateCapture(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 			return m, createEntity(m.store, result.entity)
 		}
 		return m, nil
-	case "esc":
+	case "esc", "tab":
 		cmd := m.setFocus(focusList)
 		return m, cmd
-	case "tab":
-		cmd := m.setFocus(m.nextFocusFromCapture())
-		return m, cmd
 	}
 	m.input = m.input.updateKey(msg)
 	return m, nil
@@ -396,10 +386,7 @@ func (m model) updateBrowse(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 				return m, loadEntities(m.store, m.listParams())
 			}
 			return m, nil
-		case "tab":
-			m.focus = focusList
-			return m, nil
-		case "esc":
+		case "l", "tab", "esc":
 			m.focus = focusList
 			return m, nil
 		case "ctrl+b":
@@ -423,10 +410,6 @@ func (m model) updateBrowse(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 	if m.splitDetail && m.state == stateList {
 		switch msg.String() {
 		case "tab":
-			if m.focus == focusList {
-				m.focus = focusDetail
-				return m, nil
-			}
 			cmd := m.setFocus(focusCapture)
 			return m, cmd
 		case "l":
@@ -439,6 +422,10 @@ func (m model) updateBrowse(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 				m.focus = focusList
 				return m, nil
 			}
+			if m.focus == focusList && m.railVisible() {
+				m.focus = focusTagRail
+				return m, nil
+			}
 		case "esc":
 			if m.focus == focusDetail {
 				m.focus = focusList
@@ -559,6 +546,13 @@ func (m model) updateBrowse(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 		cmd := m.setFocus(focusCapture)
 		return m, cmd
 
+	case "h":
+		if m.state == stateList && m.railVisible() && m.focus == focusList {
+			m.focus = focusTagRail
+			return m, nil
+		}
+		return m, nil
+
 	case "a":
 		if m.state == stateList {
 			cmd := m.setFocus(focusCapture)