Leader.terminal -> Leader.tab (exact tab label, case-insensitive match).
LeadTabScanner matches an exact tab->name map instead of stripping a
shared tabPrefix, and no longer merges configured leads into every
scan result -- a stale pin can no longer outlive its tab.
LeadLauncher.tabLabel() returns the configured tab directly; the
terminalId pinned-terminal fallback in liveLeads() is gone.
Config load now rejects a leftover fleet.leaders.*.terminal key
instead of silently ignoring it. primary.terminal is untouched.
Dai Ha