The editor pane showed a single buffer — opening a second file
replaced the first, even though the daemon's EditorRegistry has
always been multi-buffer (editor.list / activate / close). This wires
the UI up to that: EditorController now tracks the full open-buffer
list (via editor.list on hydrate, kept in sync by editor.opened /
closed / saved / edited events), and EditorView renders the buffers
as tabs through the shared MultitabPane — the same strip the Claude
pane uses. The daemon stays the source of truth: the local tab
controller is reconciled from it, and tab select / close route back
as editor.activate / editor.close. Reorder is disabled for now
(daemon order is authoritative).
Co-Authored-By: Claude <noreply@anthropic.com>