v1.5.4

Universal Space coverage. v1.5.3 closed panel 1; v1.5.4 closes the
remaining no-op corners: panel 3 Logs / Events / Relatives-at-depth-1
tabs each get their own cheatsheet, and empty panel 2 surfaces an
explainer instead of swallowing the keypress.

Added

• Panel 3 tab cheatsheets via Space. Logs / Events tabs each get a
  read-only popup listing j/k/u/d/G/y/z (scroll, copy, full-screen).
  Relatives tab at depth=1 (no drill chain yet) shows a drill-into
  cheatsheet (Enter to drill, Y for YAML, Esc to pop). At depth>1 the
  existing breadcrumb popup still opens.
• Empty panel 2 Space hint. When the table is empty (e.g., a
  namespace with no Deployments), Space no longer no-ops — it opens a
  popup naming the likely cause (filter on, helm-managed hidden, wrong
  ns/context) and the keys that fix each.

Changed

• SidebarHelpPopupModel → HintPopupModel. Refactored the v1.5.3
  sidebar-only popup into a generic title + rows model. One instance
  serves all six call sites (sidebar, container drill — via separate
  panel 2 menu — Logs / Events / Relatives-depth-1 / empty panel 2).
  No user-visible change beyond more places Space works.