Clicking the picker pill now opens an in-flow space-list disclosure
beneath the workspace row instead of cycling to the next space. The
list shows every space's emoji glyph + name, highlights the active one
with the accent check, and on row click switches to that space and
closes the disclosure.
Sidebar disclosure rules:
- The chevron flips ChevronDown → ChevronUp when open so the affordance
reads at a glance.
- A "Manage spaces" footer routes to ely://settings/spaces and closes
the picker.
- ElyShell carries a workspace_picker_open: bool with toggle / close /
select_space_from_picker helpers; render_sidebar_header receives a
&ElyShell so it can read the open flag without leaking shell internals
to free helpers.
The existing SelectNextSpace shortcut still routes through
cycle_to_next_space, so the keyboard cycle behaviour is unchanged.