* fix(ssh): an old SSH host converts while a relay shell named only on its tab still runs
The conversion check counted legacy pane-key aliases as terminals waiting to
reconnect. An alias only routes hook events to a pane whose terminal the lease
check, the bridge or the terminal gate already accounts for, so it no longer
blocks the move.
* Tighten the alias census comment
* Register the tab-only relay spec: typed deployment lookup, relay fence baseline, PR route
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Co-authored-by: E2E Test <e2e@test.local>