sl0p: stop hide_default_pane_names blanking the plugin API

`hide_default_pane_names` is a frame-rendering option, but it was applied
inside current_title() -- which is also what fills PaneInfo.title. Every plugin
that lists panes therefore received an empty string for any pane whose program
had never set a title.

For the bundled session manager that is untidy. For a fuzzy pane finder it is
broken: the rows are identical AND unsearchable, so the plugin's whole purpose
stops working.

The blanking moves to the frame, which already had a blank_title concept, and
current_title() goes back to reporting a real title to everything that asks.
Frames still show nothing for an unnamed pane, named panes still show their
name, and PaneInfo reports "Pane #N" again.

Changes a value rather than adding a field, so it needs no protobuf
regeneration.

Only observable without a shell that sets a title: verified by disabling the
zsh hook, where the pane finder previously listed three identical blank rows
and now lists Pane #1/#2/#3. That masking is also why this went unnoticed --
and why I flagged it twice without confirming it was actually reachable.

0 files changed, 0 insertions, 0 deletions